View source for DCL-11-005, Diablo Canyon, Units 1 and 2, Report on the Analysis of the Shoreline Fault Zone, Appendix B, Onshore-Offshore Geologic Map the Shoreline Fault Zone Study Area

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| number = ML110140408
| issue date = 01/07/2011
| title = Diablo Canyon, Units 1 and 2, Report on the Analysis of the Shoreline Fault Zone, Appendix B, Onshore-Offshore Geologic Map the Shoreline Fault Zone Study Area
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| author affiliation = Pacific Gas &amp; Electric Co
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| addressee affiliation = NRC/NRR
| docket = 05000275, 05000323
| license number = DPR-080, DPR-082
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| case reference number = DCL-11-005
| document type = Environmental Report
| page count = 112
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{{#Wiki_filter:APPENDIX B ONSHORE-OFFSHORE GEOLOGIC MAP THE SHORELINE FAULT ZONE STUDY AREA, SAN LUIS OBISPO COUNTY Shoreline Fault Zone Report, Appendix B Geology Page B-1 of 112 TABLE OF CONTENTS 1. INTRODU CTION ....................................... 
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5 1.1 Purpose and Objectives 
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5 1.2 Previous Investigations 
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5 1.3 N ew Base M ap ............................................................................................................
6 1.4 N ew D ata Sources ...........................................................................................................
6 2. M ETH OD OLO GY ............................................................................................................
7 2.1 Onshore M apping .............................................................................. 
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7 2.2 Offshore M apping ...........................................................................................................
7 3. GEOM ORPH OLO GY .......................................................................................................
10 3.1 San Luis Range ..................................................................................................................
10 3.2 Continental Shelf ..................................................................................
11 4. STRATIGRAPHY 
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14 4.1 M esozoic Form ations ....................................................................................................
14 4.2 Tertiary Stratigraphy 
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15 4.3 Quaternary Stratigraphy 
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19 5. STRU CTURE ..........................................................................................................................
20 5.1 Tectonic H istory .............................................................................................................
20 5.2 Basem ent Structures 
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22 5.3 Tertiary Structures 
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22 5.3.1 D eform ation of the Tertiary/basem ent contact ..................................................... 
.22 5.3.2 D eform ation w ithin the Obispo Form ation ...........................................................
22 5.3.4 D eform ation w ithin the Pism o Form ation .............................................................
24 5.4 Quaternary Structures 
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25 5.4.1 H osgri fault zone ....................................................................................................
25 5.4.2 N 40W fault ..................................................................................................................
27 5.4.3 Shoreline fault zone ..............................................................................................
28 5.4.4 San Luis Bay fault zone ..........................................................................................
39 6. CON CLU SION S ...................................................................................................................
43 7. REFEREN CES .......................................................................................................................
45 LIST OF TABLES Table B-1 Drop core samples from the LTSP Table B-2 Diver samples from the LTSP Table B-3 Diver samples from the 2010 campaign Table B-4 Characteristics of the N40W fault Table B-5 Characteristics of the North segment Shoreline fault Table B-6 Characteristics of the Central segment Shoreline fault Table B-7 Characteristics of the South segment Shoreline fault Shoreline Fault Zone Report, Appendix B Geology Page B-2 of 112 LIST OF FIGURES Figure B-i-1 Figure B-1-2 Figure B-1-3 Figure B-2-1 Figure B-2-2 Figure B-3-1 Figure B-3-2 Figure B-3-3 Figure B-3-4 Figure B-3-5 Figure B-3-6 Figure B-4-1 Figure B-4-2 Figure B-4-3 Figure B-4-4 Figure B-5-1 Figure B-5-2 Figure B-5-3 Figure B-5-4 Figure B-5-5 Figure B-5-6 Figure B-5-7 Areas of previous geologic mapping Comparison of (a) USGS topography with (b) the new LiDAR topography at San Luis Hill Comparison of (a) LTSP bathymetry with (b) the new MBES bathymetry at Pecho Rock Offshore samples obtained during the LTSP) and in 2010 for this study Comparison of (a) LTSP geology map with (b) the new geologic map near Olson Hill Geomorphic regions in the Shoreline fault zone study area Characteristics of the Islay and Santa Rosa Reef shelves Structure contours on top of bedrock on the Islay and Santa Rosa Reef shelves Channel profiles of the thalwegs of Islay and Pecho Creeks Migration of sand sheet along the Central segment of the Shoreline fault zone between the 2009 and 2010 MBES bathymetric surveys northwest of Olson Hill Faults and paleostrandlines in the Shoreline fault zone study area Simplified geologic map of the Shoreline fault zone study area with seismicity Stratigraphy of the coastline exposures and offshore area adjacent to DCPP Faults from geologic map overlain with composite magnetic-field anomalies from marine and helicopter surveys Generalized area of Franciscan m6lange offshore compared to magnetic-field anomalies Comparison of (a) the geology with (b) the magnetic-field anomalies in the DCPP area Comparison of (a) the Crowbar fault interpreted from the LTSP with (b) offshore faults in the Pismo Formation interpreted from this study Comap seismic-reflection lines CM-21 and CM-23 across the Hosgri fault zone and north ends of the North segment Shoreline and N40W faults Comparison of (a) MBES bathymetric image with (b) the interpreted geology and (c) paleostrandlines across the N40W fault Comparison of (a) MBES bathymetry with (b) interpreted geology and (c)paleostrandlines across the Central segment (C-1) of the Shoreline fault zone west of DCPP Comparison of (a) MBES bathymetry with (b) interpreted geology and (c)paleostrandlines across the Central segment (C-2) of the Shoreline fault zone southwest of the DCPP entrance Comparison of (a) MBES bathymetry with (b) interpreted geology and (c)paleostrandlines across the Central segment (C-2) of the Shoreline fault zone west of Olson Hill Shoreline Fault Zone Report, Appendix B Geology Page B-3 of 112 Figure B-5-8 Comparison of (a) MBES bathymetry with (b) interpreted geology and (c).paleostrandlines across the Central segment (C-3) of the- Shoreline fault zone west of Rattlesnake Creek Figure B-5-9 Comparison of (a) MBES bathymetry with (b)'interpreted geology and (c)paleostrandlines across the South segment of the Shoreline fault zone southwest of Point San Luis Figure B-5-10 Apparent offset of Cretaceous sandstone beds across the Rattlesnake fault, San Luis Bay fault zone LIST OF PLATES Plate B-1A North section geologic map, Morro Bay to Point Buchon Plate B-1B Central section geologic map, Point Buchon to Double Rock Plate B-IC South section geologic map, Double Rock to San Luis Hill Plate-B-1D Southeast section geologic map, Point San Luis to Pismo Beach LIST OF ATTACHMENTS Attachment 1 2010 Dive Sample Descriptions Shoreline Fault Zone Report, Appendix B Geology Page B-4 of 112 
: 1. INTRODUCTION This appendix presents a comprehensive geologic map from a compilation of existing and new geologic mapping and geophysical data both onshore and offshore in the Shoreline fault zone study area. The study area extends from the western slope of the Irish Hills on the east to the edge of the continental shelf at the Hosgri fault zone on the west, and from Estero Bay on the north to Pismo Beach on the south (Figure B-1-1). The geologic map is presented in four plates at 1:12,000 scale (Plates B-1A to B-ID).1.1 Purpose and Objectives The purpose of creating an onshore-offshore geologic map of the study area is to place the Shoreline fault zone in its geologic context. The objectives of the mapping include: 1. Complete a geologic map of the study area using previous and new field mapping plus the newly acquired MBES and LiDAR images, dive samples, seismic-reflection profiles, and high-resolution helicopter magnetic field data;2. Characterize the length, segmentation, style of faulting, and slip rate of the Shoreline fault zone;3. Accurately locate the fault trace where it lies offshore of DCPP;4. Assess the relation of the mapped traces of the Shoreline fault zone to the seismicity lineament that originally defined the Shoreline fault; and 5. Evaluate the evidence, if any, of late Quaternary displacements on the fault.-I, 1.2 Previous Investigations Existing onshore geologic maps within the DCPP site vicinity are shown on Figure B-i-1.Mapping of the Irish Hills (i.e., Point San Luis and Morro Bay topographic quadrangles) was completed at 1:24,000-scale by Hall (1973a) and later incorporated into a regional compilation by Hall et al. (1979) with minor revisions at 1:48,000 scale. Mapping of the Arroyo Grande topographic quadrangle at 1:48,000-scale by Hall (1973b) includes the Avila Beach and Pismo Beach area. These quadrangle maps were adopted with revisions for geologic maps included in the DCPP Final Safety Analysis Report (FSAR) (PG&E, 1975) and in the LTSP (PG&E, 1988;1991) at 1:12,000 scale. A geologic map of the Morro Bay South topographic quadrangle was recently produced at 1:24,000 scale by the California Geological Survey and includes the northern part of the Irish Hills (Wiegers, 2009).Detailed geologic maps (larger than about 1:6,000 scale) in the immediate area of DCPP include a map of coastline bedrock exposures from Discharge Cove to Green Peak completed in 1970 (PG&E, 1975). More recent geologic maps of the DCPP site are presented in the FSAR for the Independent Spent Fuel Storage Facility (PG&E, 2002).Offshore geologic mapping in the DCPP vicinity was initiated by oil exploration efforts and was expanded during a comprehensive investigation performed for the LTSP (PG&E, 1988).Shoreline Fault Zone Report, Appendix B Geology Page B-5 of 112 Bathymetric data available at that time were insufficient for evaluating submarine landforms, and offshore interpretations focused mainly on ship-borne seismic-reflection profile line data and point sampling campaigns using drop coring equipment and divers (Niemi et al., 1987; PG&E, 1989).Areas of late Quaternary deformation and uplift in the Irish Hills are delineated on a map of onshore Quaternary deposits and marine terrace shoreline angles along the southwest coast of the Irish Hills, as well as a map of offshore wave-cut platforms using the bathymetric data available at the time (PG&E, 1988; 1991; Hanson et al., 1994).1.3 New Base Map An important advancement in geologic mapping of the study area has been the acquisition of accurate and detailed topographic and bathymetric data. Because of the benefits of a better geologic interpretation of the study area and adjacent areas, PG&E was permitted to use the San Luis Obispo County Interferometric Synthetic Aperture Radar (INSAR) Digital Elevation Model (DEM) that has an accuracy of 16 feet (5 meter) raster grid resolution.
This dataset is a substantial improvement over the existing U.S. Geological Survey 40-foot topographic contour maps of the area (Morro Bay South and Port San Luis quadrangles, scale 1:24,000).
The INSAR DEM was supplemented between Islay Creek and Point San Luis with newly acquired aerial photography (scale 1:12,000), and a LiDAR survey of the coastal strip at one of the lowest tides of the year (described in Appendix G). The LiDAR DEM has an accuracy of 5 centimeters with pixel resolution of 0.2 meters. Figure B-1-2 compares maps of a selected area at San Luis Hill that illustrates the improvement in the LiDAR-derived topography over the USGS topographic map.The offshore bathymetry fronting the Irish Hills has been improved substantially with the Multibeam Echosounder (MBES) survey of the continental shelf between Estero Bay and Pismo Beach (described in Appendix F). The spatial resolution for this new bathymetry in water depths less than 50 meters is 1 meter, and in water depths greater than 50 meters the resolution is 2 meters. Figure B-1-3 illustrates the improvement in bathymetry in the area around Pecho Rock.Because of navigation hazards, shallow water, kelp beds, and submerged rocks, the bathymetry of the strip adjacent to the coastline as well as over and around shallow rocks was not obtained.1.4 New Data Sources High-resolution seismic-reflection profile data were obtained by the USGS along northeast-southwest transect lines within the Shoreline fault study area (described in Appendix H). The high-resolution seismic profiles provide a complementary dataset to deeper-penetrating common-depth point seismic-reflection profiles evaluated during the LTSP (PG&E, 1988). The seismic-reflection profile data were collected as close as the boat could safely approach the rocky coastline to offshore beyond the Hosgri fault zone. Trackline spacing is a nominal 800 meters (0.5 miles) with 400-meter spacing across the Shoreline fault zone, Data records extend to about 0.45 seconds two-way-travel time (338 meters at 1500 m/sec). Seismic signal depth penetration ranges from zero (in some areas of Franciscan Complex) to about 200 meters in areas of soft sediment cover (including within and adjacent to the Hosgri fault zone). Recent reprocessing of Shoreline Fault Zone Report, Appendix B Geology Page B-6 of 112 a few seismic-reflection profiles improved resolution and reduced spurious noise relative to the initial processing done by the USGS.The magnetic field within the study area has been measured in several surveys to help identify rock units and structures having distinct magnetic signatures.
Recently acquired magnetic field data by the USGS include an overland fixed-wing aerial magnetic survey and a marine magnetic survey with ship line spacing at 400 meters (details in Appendix D). These surveys were supplemented by a high-resolution helicopter magnetic survey across the Irish Hills coastline at 150 feet "above deck" to better define magnetic anomalies associated with the Shoreline fault zone and to gain detailed data in the gap between the onshore and offshore measurements (Appendix D).2. METHODOLOGY 2.1 Onshore Mapping Detailed onshore geologic mapping documents structural and stratigraphic relationships exposed in sea cliffs and wave-cut platforms along 17 kilometers of coastline to the northwest and southeast of DCPP. The objectives of this mapping effort were to identify and characterize the range and distribution of bedrock lithologies, to measure bedding attitudes, and to document structural discontinuities.
Mapping was conducted during the spring months of 2009 and 2010 by Stephen Thompson, Michael Angell, Andrew Lutz, and Cooper Brossy of Fugro-William Lettis Associates (FWLA). The mapping was peer reviewed in the field by William Lettis (FWLA), Ray Weldon (Consultant, University of Oregon) and William Page (PG&E Geosciences Department).
Geologic mapping was conducted in accordance with standard field techniques described in sources such as Compton (1985). This included examination of natural outcrop exposures and road-cuts, and these observations were located spatially by inspection of geo-registered aerial photographs and commonly confirmed by recording positions with a handheld GPS unit.Orientations of bedding planes, fault planes, and joint planes and lineations were measured with a transit compass. Bedding features were considered carefully before measuring and were selected only when there was clear evidence of original horizontality, including consistent orientations of laminations and textural grading. Measurements of bedding attitudes (both strike direction and dip amount) are accurate to within 5 degrees. Bedding attitudes elsewhere in the DCPP site area were compiled from pre-existing sources (PG&E, 1975; 1988; 1991; 2002; Hall et al., 1979) and checked for accuracy by examining aerial photographs.
These prior measurements were included after checking for consistency with structural fabric characteristics defined by other available data.2.2 Offshore Mapping 2.2.1 MBES bathymetric data The recently acquired MBES bathymetric data (Appendix F) allowed detailed interpretation of stratigraphic and structural relationships and seafloor geomorphology in the offshore area between Morro Bay and Pismo Beach. The bathymetric data with one- to two-meter pixel Shoreline Fault Zone Report, Appendix B Geology Page B-7 of 112 resolution covers large areas of nearly continuous rock exposure.
The general quality of the 2008 and 2009 MBES bathymetric data is excellent.
The bathymetry data generally extend fiom as close to the shoreline as the boat could safely approach out to the approximate"seaward limit of bedrock outcrops.
Sea floor features such as sediment bedforms (mobile sand sheets) and bedding ridges with a few tenths of a meter relative elevation change are imaged.Where bedrock is imaged in the MBES bathymetric data, surface roughness and fabric allowed correlation and interpretation of different lithologies and structures.
Derivative maps of the MBES data, particularly shaded-relief maps presented at different illumination angles and slope maps, enhanced the view of erosional patterns that are consistent withinclined bedding, folds, and structural and stratigraphic discontinuities (faults and unconformities) that truncate or cross-cut bedding and structures.
Bedding strike of laterally continuous strata can be resolved in the MBES bathymetric data with a high degree of confidence, and dip direction may be recognized based on erosional patterns, local inclination or slope, and structural and stratigraphic position.Dip angle, however, is not well constrained from the MBES image. Estimated dips from the MBES bathymetric data were consistently lower when compared to measured dips on strike with the same beds onshore. The reason for this under-prediction is probably either (1) the data have too large a pixel size to measure dips on rather narrow bedding surfaces, or (2) erosion has modified original dip slopes. Identification of lithologic units in the bathymetric data was based on a number of criteria, including: 
(1) diver sample and drop-core data (see description below);(2) correlation with onshore data from existing maps and from recent coastline mapping (described above); and, (3) extrapolation of bathymetric texture from well-constrained lithologic areas to less well-constrained areas.2.2.2 Sea floor samples Direct observation of offshore lithology was performed by diver sample and drop core campaigns conducted for the LTSP (PG&E, 1991), and is supplemented by an additional diver sample campaign conducted in July 2010. Locations of drop cores collected for the LTSP were recorded using a LORAN C device and are assumed to be accurate within 10 to 20 meters.Locations of diver samples collected for the LTSP were, calculated by using LORAN-C readings'for the dive boat and then factoring divers' estimates of direction and distance from the vessel.The reported positions of these diver samples are assumed to be accurate within 50 to 100 meters. The LTSP samples (including descriptions) are compiled in Table B-I for the drop cores and Table B-2 for the diver samples. Sample locations are plotted on Figure B-2-1 and are shown with revised interpretations on Plates B-1A to B-iD.In the course of interpreting the MBES data, alternative lithologic interpretations were considered for these older samples in order to resolve inconsistencies between onshore and offshore data. Because the LTSP samples are not available to review, only those samples that were inconsistent with more recent samples or with the initial structural and stratigraphic interpretation of the MBES data Were reviewed critically and often reinterpreted.
In particular, several fine-grained samples previously interpreted as Pismo Formation were reinterpreted as fine-grained interbeds within Cretaceous sandstone, several sandstone samples classified as Franciscan greywacke were reinterpreted as Cretaceous sandstone, and several fine-grained samples classified as Monterey Formation were reinterpreted as fine-grained facies within the Obispo Formation.
Shoreline Fault Zone Report, Appendix B Geology Page B-8 of 112 Fifty new diver samples were collected under the supervision of Andrew Lutz (FWLA) who was knowledgeable of the stratigraphic units and their variation from detailed mapping along the coast described above. The July 2010 campaign used a targeted strategy to classify different areas of distinct bathymetric texture and specific locations where preliminary interpretations suggested a conflict of interpreted formations between the LTSP and the current mapping.Sample locations were recorded using a handheld GPS device on the dive vessel and are assumed to be accurate to within 10 to 20 meters. Samples from this most recent dive campaign are located on Figure B-2-1 and summarized on Table B-3. Sample descriptions and interpretations are in Attachment 1 to this Appendix.2.2.3 High-resolution seismic-reflection profiles The high-resolution sparker seismic-reflection profiles collected by the USGS in 2008 and 2009 were interpreted using the Kingdom Suite Program by Seismic MicroTechnology to delineate structural features.
The sparker data provided improved resolution of shallow structures over previous datasets, and structures delineated from the seismic lines were integrated with the offshore geologic map.2.2.4 Integration of onshore and offshore mapping All the primary data sets used in the current map exist in digital format and were integrated into a GIS database.
The interpretive information (e.g., geological units and contacts, fold axes, and fault traces) were compiled digitally or were hand-annotated on the base maps, scanned, and then digitized.
The detailed geologic map is presented in four sheets (Plates B-1A to B-1D) at a scale of 1:12,000.
The map sheets cover the area from Morro Bay in the north to San Luis Obispo Bay in the south. The map sheets extend from the shoreline area on the east to 3 to 12 kilometers offshore.
The nriaps show onshore topographic features, onshore geologic units and structures, offshore core and diver sample locations and units, MBES bathymetry images, and point locations where structures were observed in the seismic-reflection profiles.
Geological features interpreted from the data sets and shown on the sheets include geological units and contacts, fold axes, and fault traces.Offshore geologic mapping was correlated with existing onshore geologic maps by considering the projection of the geologic units, faults and contacts into the area covered by MBES bathymetric data. Tertiary rock contacts were mapped along prominent beds visible in the bathymetric data and bedding was.traced through folds. Pre-Tertiary (basement) lithologic boundaries were mapped by following prominent changes in bathymetric fabric that are consistent with sea floor samples and magnetic susceptibility data (Appendix D). Stratigraphic units mapped southwest of the Shoreline fault are generally not identified to the member or subunit level due to reduced control on stratigraphic position and difficulty in identifying the rock type from texture alone without sufficient samples to confirm the selection of lithology.
The magnetic field data were interpreted by overlaying the total magnetic intensity and reduction-to-pole images (Appendix D) on a preliminary draft of the geologic map to help define the limits of the main magnetic rock types in the area, particularly diabase in the Obispo Formation, Franciscan Complex greenstone, and Jurassic pillow basalt. Several contacts were adjusted to better match the magnetic field data.Shoreline Fault Zone Report, Appendix B Geology Page B-9 of 112 The high-resolution seismic-reflection profiles were used in the areas of the shelf covered with sediments to map folds and faults in the Tertiary rocks and to evaluate potential deformation of wave-cut platforms (see also Appendix I). The integrated map that exhibits the interpreted geology using all the data sources allows for a greatly improved geologic map offshore.
As an example, Figure B-2-2 compares the geology mapped onshore and offshore near Olson Hill and illustrates the improvement in the geologic interpretation over previous efforts.Folds and faults interpreted from the MBES bathymetric and seismic-reflection profile data sets are separately identified.
Structures mapped primarily on the basis of MBES bathymetric imagery are shown as thin black lines. Folds are annotated with arrows indicating fold type and plunge if identified.
Fault offsets are indicated by a UP/DN symbol for vertical displacement if that can be determined from the MBES bathymetric data. Solid lines indicate a feature observed in the MBES bathymetric imagery. Dashed lines indicate the inferred continuation of the structure (folds and faults) where sea floor evidence is not present due to sediment cover.Folds and faults interpreted from the seismic-reflection data are shown as yellow squares at the intersection of the seismic line and the structural feature. Correlated structures are indicated by thin lines for older faults and all fold axes. If faults are interpreted as buried by 2 to 3 meters or more of sediment the fault is shown as a dotted line. Faults that are strands of the Hosgri fault zone are shown as thick black lines. Solid lines indicate that in at least one location the fault was interpreted to intersect the sea floor; dotted lines indicate the fault is everywhere interpreted as buried by 2 to 3 meters or more of sediment.
Dashed lines with query marks indicate there is uncertainty about the line-to line correlation or continuation of the structural feature.Buried wave-cut platforms and shoreline angles interpreted from the seismic-reflection profile data are presented in Appendix I.Seismic reflection, side-scan sonar, and bathymetric data collected for the FSAR and LTSP between 1975 and 1988 were used to produce Structural Trend and Sediment Isopach maps in this area for the LTSP (PG&E, 1990). These maps were compared to the current maps but the previous data were not directly incorporated into the current mapping program as the basic data sets are currently in analog, not digital formats.3. GEOMORPHOLOGY The study area lies along the central California coast, between Morro Bay and Pismo Beach, southwest of San Luis Obispo. The geomorphic regions in the area include the Irish Hills, the marine terrace flanking the western margin of the hills, the continental shelf, and slope offshore.The continental shelf is subdivided into the Islay and Santa Rosa Reef shelves (Figure B-3-1). A third shelf, named the San Luis shelf, is located east of the Santa Rosa Reef shelf in San Luis Obispo Bay and is discussed in Appendix I.3.1 San Luis Range Irish Hills -The Irish Hills are an oval-shaped, northwest-trending range, 18 km long and 14 km wide, that form the northern end and highest part of the San Luis Range, a pr6minent west-northwest-trending topographic and structural high. The Irish Hills are bordered on the north Shoreline Fault Zone Report, Appendix B Geology Page B-10 ofl112 and west by the Los Osos Valley and the coastal embayment formed by the Estero and Morro bays and on the south and east by San Luis Obispo Creek Valley and San Luis Obispo Bay. The crest of the Irish Hills reaches elevations of 1600 to 1800 feet (500 to 550 meters) with the highest ridges near the head of Diablo Creek, including Saddle Peak (554 m; 1819 feet). Point San Luis and San Luis Hill (660 feet) are separate from the Irish Hills and form a prominent point on the southwest side of the range. Islay, Coon, Diablo, See, and Pecho creeks originate near the center of the range and form a crude radial pattern dominated by reaches that follow the northwest structural grain as canyons cut into the hills. These creeks formed as consequent streams as the range emerged from the Pacific in the middle Pliocene; but as erosion continued, the creeks favored and eroded along the northwest structural grain of bedding along most of their lower reaches. The top of the range has a broad accordance.
of hilltops that form a surface that slopes gently east and southeast; this surface records a degraded late-Pliocene erosion surface (PG&E, 1988; 1991).Marine terraces onshore -Bordering the Irish Hills and the coastline is a narrow, seaward-sloping terrace that is up to 1 kilometer wide. The east side is bordered by the steep slopes of the Irish Hills and the west side by the sea cliffs that form the coastline whose western-most extremity is Point Buchon. This terrace is underlain by alluvial fan deposits that are in turn underlain by multiple marine wave-cut platforms and paleostrandlines whose seaward edges are exposed in the sea cliffs and in some valleys. The landward side of the terrace in the north reaches up to 36 meters elevation but is at only 12 to 18 meters in elevation in the south. This terrace was carved into the Irish Hills by wave erosion during the late Pleistocene sea-level high stands at approximately 81,000 to 240,000 years ago (Hanson et al, 1994) and subsequently covered by alluvial fan deposits.
This is discussed in more detail in Appendix I.The western edge of the terrace consists of rugged headlands, sea cliffs, coves, arches, stacks, and a few pocket beaches, the largest of which is at the mouth of Islay Creek. The sea cliffs on the southeast side of Point San Luis approach 60 meters elevation but are only 12 to 24 meters elevation on northwest of Point San Luis to Islay Creek.Where the northwestern Irish Hills north of Islay Creek terminate at Morro Bay, the marine terrace and lower slopesare covered by Pleistocene and modern sand dunes. The older dunes are stabilized by vegetation cover. In contrast, the marine terrace is nearly absent at the southern end of the Irish Hills between Point San Luis and San Luis Obispo Creek. Here, the coastline consists of a bluff on the west and a steep hillslope with a narrow beach on the east. Where San Luis Obispo Creek enters San Luis Obispo Bay there is a small filled estuary and Avila Beach.3.2 Continental Shelf The continental shelf offshore of the Irish Hills slopes gently westward.
The shelf here is 5- to 10-kilometers wide and lies between the coastline and a prominent break-in-slope to the steeper (1.0' to 2.00) inclined continental slope at water depths of 100 to 225 meters, which is generally coincident with the Hosgri fautlt zone. Numerous rocks extend above sea level close to the shoreline, including Lion Rock near of Diablo Canyon, and Pecho Rock west of Olson Hill. The Santa Rosa Reef and Wesdahl Rock are shallow bedrock projections west of Point San Luis that lie about 6 meters below mean sea level.Shoreline Fault Zone Report, Appendix B Geology Page B-1 1 of 112 Niemi et al. (1987), who first described the offshore shelf for the LTSP, note that much of this"inner" shelf is a rocky near-shore zone corresponding to the general seaward limit of the sea floor bedrock outcrops at approximately 70 to 80 meters depth. They point out that the rocky near-shore shelf is buried to the north and south by on-lapping Quaternary marine sediments in Estero and San Luis Obispo bays and to the west by sediment of the outer shelf.The inner shelf is underlain by folded, fractured and faulted bedrock of Cretaceous and Tertiary rocks that has been planed by wave activity and etched by differential erosion during multiple sea-level transgressions and regressions in the Quaternary.
As a result, the upper surface of bedrock is essentially planar but with a rough relief generally less than 5 meters (Figure B-3-2).The rocky bedrock shelf is locally incised by stream channels and troughs eroded by marine processes into the less resistant rocks. The more resistant rocks preserved in many places are represented by submerged paleosea stacks, wave-cut platforms, paleosea cliffs, and paleostrandlines (former coastlines) that formed during one or more Pleistocene sea-level stillstands.
Islay and Santa Rosa Reef shelves -Analysis of the MBES bathymetry allows the division of the inner continental shelf off the Irish Hills into two parts, the Islay shelf on the north and the Santa Rosa Reef shelf on the south (Figure B-3-2). Both shelves have a rocky near-coast portion and a sediment-covered portion further offshore.
The Islay shelf has a steeper slope than the Santa Rosa Reef shelf that is reflected in the structure contours on top of bedrock (Figure B-3-3).These are further described in Appendix I.Paleo-stream Channels -Prominent submerged sediment-filled paleo-stream channels and narrow to moderately wide paleo-valleys are preserved in the near-shore shelf (Plates B-i A to B-ID; Figure B-3-3). Although generally covered by unconsolidated sediment (mobile sand sheets), the channels range up to several kilometers long and appear to broaden into valleys at their distal western ends. The unconsolidated deposits filling paleo-channels are part of the mobile sand sheets and other fine-grained marine deposits; one seismic-reflection profile indicates the depth of sediments in the Islay Creek channel is about 8 meters. Remnants of alluvium and older marine deposits may underlie the surficial sand deposits.Four prominent submerged stream channels are preserved in the Tertiary sedimentary rocks in Islay shelf. The northern-most channel is the shortest at approximately 800 meters long; it is preserved completely within sedimentary rock of the Pismo Formation offshore and is aligned with the mouth of Hazard Creek on shore. The longest (approximately 4.5 kilometers long), channel with the largest and best developed meanders is the Islay Creek channel. This channel is located just offshore of Islay Creek where its headward parts appear to have eroded across a north-northwest striking fault zone. This channel extends west of a rocky shelf to where it is buried by a mobile sand sheet that fills a shallow bedrock valley. The third channel is approximately 2.5 kilometers long and approximately 75 meters wide at its mouth. In bedrock the channel has well-developed incised meanders.
The channel is located just offshore of Coon Creek, north of Point Buchon. The fourth channel is a pair of short, approximately 1.5-kilometer-long channels that head toward a small cove south of Point Buchon, but do Aot appear to align with any onshore stream. These channels broaden to the west into what may have been a wide valley or lagoon. The two channels are structurally controlled with one aligned along a fault and the other eroded along bedding.Shoreline Fault Zone Report, Appendix B Geology Page B-12 of 112 Three channels are carved into the Cretaceous sandstone in the Santa Rosa Reef shelf (Plate B-IB). All are 1 to 2 kilometers offshore and none have clear onshore equivalents.
The northern channel is a narrow and weakly meandered channel that trends southwest.
This channel is approximately 2.5 kilometers long and is roughly on trend with three small creeks: Irish, Pecho and Rattlesnake Creeks. At its landward end, the channel makes a right bend of approximately 200 meters along an interpreted fault. South of the channel is a network of intersecting channels that trend northeast, west-southwest and West. Individual channels are approximately 
.1 to 2.5 kilometers long with the southern-most channel being the longest. The southern west-trending channel has eroded along a fault in the sandstone.
The third channel is a kilometer offshore of Point San Luis. It trends westerly and parallel to the coast. It is narrow and approximately 1 kilometer long.The larger channels generally exhibit meanders showing that erosion occurred subaerially when the streams were near or at base level probably during one or more prolonged sea-level lowstands during the late Pleistocene.
This interpretation is supported by the smooth concave-up profiles of the Islay Creek and-Pecho Creek channels (Figure B-3-4). The absence of prominent knick points shows that these streams eroded their channels to a base level offshore during sea-level low stands.The preservation of the paleo-channels below 20 meters water depth attests to the minimal erosion on the shelves during the rapid sea-level rise that began after the Last Glacial Maximum (LGM) 20,000 to 22,000 years ago. In contrast, the near-absence of paleo-channels above 20 meters water depth probably results from erosion since the rate of sea-level rise slowed about 7,000 years ago (Figure B-3-4 and Appendix I).The gap between the head of the offshore channels and the onshore streams results from the Holocene erosion and cliff retreat that destroyed the channels since approximately 7,000 to 5,000 years ago (Figure B-3-4). The amount of Holocene erosion on the northern Islay shelf may be estimated based on the preservation of the paleo-channel of Islay Creek. The Islay Creek paleo-stream channel is incised approximately 1 to 2 meters into the 800-meter-wide Holocene wave-cut platform and approximately 8 meters into Pismo Formation rock west of the Holocene platform.
The 6 to 7 meters of differential stream incision may represent the amount of vertical lowering of Pismo Formation strata in approximately 7,000 years.Sand Sheet 'Dunes' -Thin mobile sediment (sand) deposits cover parts of-the near-shore continental shelf to water depths of 80 meters (Plates B-lA to B-ID). These are well-defined, low, less than one meter high, dune-like features with long wave-lengths, approximately 25 to 125 meters (Figure B-3-2). The sand sheets cover marine sediments, and on-lap low bedrock outcrops, partly fill low areas, including paleo-stream channels, in the exposed bedrock platforms, and undoubtedly cover shallow marine deposits from the post-LGM transgression and locally earlier transgressions or sea-level stillstands.
The sand sheets are particularly well expressed on the outer, sediment-covered part of the Islay shelf, opposite Islay Creek to Diablo Canyon where sand sheet fronts (lee slope) are perpendicular to a $35&deg;E direction.
The morphology appears to be formed by strong southeast-flowing currents most likely generated from storm events and may vary seasonally, or -from particularly severe storms. For example, sand sheets in the Point Buchon area bathymetrically imaged both in 2007 and 2009 have been reported to cover upwards of 80% of what was rocky habitat in 2007 in the 20 to 10 meter depth zone with half a meter of sediment (written communication, Rikk Kvitek to Sam Johnson, October 30, 2009).Shoreline Fault Zone Report, Appendix B Geology Page B-13 of 112 Migration of the sand sheets northwest of Olson Hill is documented from MBES bathymetric surveys undertaken in 2009 and 2010 in which previously buried bedrock is exposed (Figure B-3-5). In addition, Figure B-3-5 shows two pockmarks on the 2009 bathymetry that are absent in the 2010 bathymetry.
If the pockmarks are real (and related to episodic expulsion of gas or fluids) and not data artifacts, their disappearance also indicates the mobile, ephemeral nature of the sand sheet deposits.
Presumably sand sheets located in deep water are mobilized during strong winter storms with large waves that mobilize the sands in the deeper waters. Their age is estimated to range from modem to less than a few hundred years.Paleostrandlines 
-The rocky inner continental shelf is characterized by bedrock at the seafloor and thin, local deposits of Quaternary sediment.
Numerous submerged paleostrandlines and features related to old shorelines along the coastline are preserved in the offshore bedrock, both exposed and where covered with sediment (Figure B-3-6). Offshore wave-cut platforms and associated paleostrandlines and their use as late Quaternary strain gauges are discussed in Appendix I.4. STRATIGRAPHY The sequence of bedrock lithologies mapped in the coastline sea cliffs and wave-cut platforms to the north and south of DCPP and the lithologies interpreted from diver samples and bathymetry data offshore are generally very consistent with the onshore map relationships described by Hall (1973a; 1973b), Hall et al. (1979), and PG&E (1988; 1991). The rocks described in this Appendix include two Mesozoic formations, Franciscan Complex and Cretaceous sandstone, which are considered basement rocks, and three Tertiary marine formations, Obispo, Monterey, and Pismo, each with basal unconformities.
Plates B-1A to B-ID and the summary geologic map (Figure B-4-1) show the different formations and Figure B-4-2 is the stratigraphic column based on Hall (1 973b). In addition; Quaternary marine terraces and their associated deposits and marine sediments occur in the area.4.1 Mesozoic Formations Pre-Tertiary rock is exposed between the Hosgri fault zone on the west and the San Miguelito fault on the east in the southern half of the Shorelinefault study area. These rocks consist of fault-bounded slices of the Jurassic-Cretaceous Franciscan Complex (JKf) and Cretaceous sandstone (Ks). This group of rocks was extensively deformed in a subduction zone accretionary prism. Tertiary strata on-lap and locally are faulted against the pre-Tertiary rock.4.1.1 Franciscan Complex Franciscan Complex rocks include a chaotic assemblage of various lithologies, including fine-grained metavolcanic rocks (greenstone, KJmv), sheared claystone (melange, KJf), glaucophane schist, serpentinite, and chert. The greenstone is dark greenish gray with common very fine quartz and calcite veins, and the glaucophane schist is bluish to greenish gray with very fine quartz veins and a pervasive shear fabric. The greenstone and glaucophane schist are associated with a greenschist facies and strong magnetic-field anomalies observed offshore of San Luis Hill, along the south side of the San Miguelito fault, and elsewhere west of the Shoreline fault zone (Figure B-4-3). Onshore the m6lange is black claystone with a pervasive shear fabric and Shoreline Fault Zone Report, Appendix B Geology Page B-14 of 112 includes pebble- to cobble-size angular clasts of fine-grained lithic sandstone (greywacke).
The mdlange is exposed in narrow bands along the coastline north and south of Olson Hill and is associated with chert and greywacke exposures.
The chert is reddish brown to light brown with prominent banding (exposed at Olson Hill and Double Rock).The texture of Franciscan Complex rocks in the MBES bathymetric data is variable, due to the highly variable levels of erosional resistance among the different rock types: Areas of the sea floor with diver samples or drop core samples identified as metavolcanic rock or glauconite schist (Plate B-iC) exhibit a hackled, isotropic texture in the MBES bathymetric image. The m6lange is expressed as narrow to wide, easily eroded low areas with various-sized knockers of resistant greenstone and Cretaceous sandstone protruding above the general m6lange surface. In the southern Santa Rosa Reef shelf the m6lange separates large Cretaceous sandstone terranes and other rock types, but toward the north it is more localized near the shoreline and separates Tertiary strata from Cretaceous rocks along the coast south of Lion Rock. The mdlange on the sea floor where exposed above the sand sheet is a low-relief, smooth surface with a shallow dimpled texture (Figure B-4-4). Some planar seafloor areas that are smooth but have a significant number of rocks three meters or higher above a low-relief bedrock plane or sand sheet are interpreted as underlain by m6lange with rock knockers.
Strong magnetic field anomalies are associated with the m1lange. The South and Central segments of the Shoreline fault zone, discussed in Section 5.4.3, are located within the m61ange.4.1.2 Cretaceous sandstone Cretaceous sandstone (Ks) exposed along the coast onshore south of DCPP is brown, thickly bedded, fine- to medium-grained greywacke.
Grain lithologies are dominantly quartz with minor amounts of feldspar and lithic grains. Interbeds of siltstone and sandy siltstone included within the exposures of Cretaceous sandstone are rare.Regionally, greywacke is the most abundant rock type within the Franciscan Complex (Hall, 1973b) but is only exposed in small pods in association with m6lange along the coastline in the study area. This relative lack of onshore greywacke exposures is a leading motivation to reinterpret certain diver samples and drop core samples from the LTSP as Cretaceous sandstone instead of Franciscan Complex greywacke (Tables B-1 and B-2). Reinterpretation of these samples provides a simpler and more consistent geologic map that more closely resembles the local onshore geology. Silt beds within the greywacke deposits are locally extensive and samples of these silty interbeds were recovered offshore of Olson Hill during the most recent diver sampling campaign (Table B-3). Recognition of these silt interbeds in the offshore provided a good criterion to reinterpret fine-grained siltstones previously mapped as Pismo Formation and reclassify them as Cretaceous sandstone (Table B-3). The MBES bathymetry images the Cretaceous sandstone as a homogenous, rough textured outcrop with consistent differentially eroded beds. Locally the texture records crude bedding.4.2 Tertiary Stratigraphy Along the coastline and east of the Shoreline fault zone, the Tertiary section is exposed south of DCPP at the base of Green Peak and is continuously exposed as younger strata to the north-northwest beyond Islay Point and into Estero Bay (Plates B-lA and B-1B; Figure 4-1). West of the Shoreline fault zone, the offshore Tertiary section is exposed northwest of an unconformity Shoreline Fault Zone Report, Appendix B Geology Page B-15 of 112 with pre-Tertiary rocks that lies southeast of DCPP and becomes younger to the west and northwest towards the Hosgri fault zone (Plate B-iC). Additional Tertiary strata are exposed east of the southern end of the Shoreline fault zone, within San Luis Obispo Bay and onshore to the northand east (Plate B-iD). The majority of the Tertiary section is composed of three formations, the Miocene Obispo, the Miocene Monterey, and the Miocene-Pliocene Pismo Formations.
Each of these formations is bounded with a basal unconformity.
4.2.1 Tertiary/basement contact The basal contact of the Tertiary section is exposed in three locations: 
(1) in the Santa Rosa Reef shelf, southwest of San Luis Hill; (2) along the base of Green Peak south of DCPP; and, (3)offshore on the east side of San Luis Obispo Bay (Plates B-lB to B-iD). Along the base of Green Peak, the basal contact of the Tertiary section is generally concealed and is an intrusive contact between Obispo Formation diabase and basement rock (Hall, 1973a; Hall et al., 1979).Directly to the northeast this contact is a moderately dipping depositional contact with Rincon and Vaqueros Formations overlying basement rock (Hall, 1973a). Farther northeast the base of the Tertiary section is truncated by the San Miguelito fault. At an inaccessible coastline exposure south of DCPP, the base of the Tertiary section appears as a subvertical.fault or possibly intrusive contact between Obispo Formation diabase and Franciscan Complex rocks (Plate B-1B). Farther west the base of the Tertiary is truncated along the Shoreline fault zone that juxtaposes Obispo diabase and basement rocks.The lowermost, Tertiary section in the San Luis Obispo region includes the Vaqueros Sandstone and Rincon Shale, locally representing a total of approximately 180 meters feet of marine conglomeratic sandstone and interbedded shale and tuff (Hall, 1973b). These units were not recognized along the DCPP coastline exposures, presumably because they (1) have been truncated by Tertiary faulting, (2) have been obscured by intrusion of the large diabase sill at the base of the Obispo Formation, (3) were not deposited in this portion of the Tertiary basin, or.(4)have been mapped as lower Obispo Formation.
However, offshore in the Santa Rosa Reef shelf, the basal Tertiary section is characterized by a package of thin, concordant beds that overlie weakly bedded Cretaceous sandstone (Plate B-iC). This may be thin Vaqueros Sandstone and/or Rincon strata that off-laps basement rock, but there are no samples to confirm this interpretation.
For mapping purposes these rocks are included w ithin the Obispo Formation.
Near the town of Avila Beach the base of the Tertiary section is constrained to lie between basement rocks on the west side of San LuisObispo Creek and Obispo Formation exposures on the east side of San Luis Obispo Creek. The fault or unconformable contact can be projected offshore but is concealed beneath sand and is inferred to separate exposures of Obispo resistant tuff on the east side of San Luis Obispo Bay from basement rock of San Luis Hill. The degree of late Tertiary deformation of this contact is unclear and difficult to evaluate due to lack of exposure.4.2.2 Obispo Formation The Obispo Formation (Tmo) is a roughly 1300-foot-thick section of marine volcanic and volcaniclastic deposits (Hall, 1973a; Hall et al., 1979) and occurs throughout the Shoreline fault study area (Plates B-1A to B-iD). Lithologies and facies associations within the Obispo Formation vary considerably on a regional basis (e.g., Hall et al., 1979), but along the coastline of the Irish Hills three subunits within the Obispo Formation are recognized:
resistant tuff (Tmor), fine-grained sandstone and claystone (Tmof), and intrusive diabase (Tmod). Tuff within Shoreline Fault Zone Report, Appendix B Geology Page B-16 of 112 the Obispo Formation has been dated at 15.5 to 15.3 million years before present (Ma) (Turner, 1970).The resistant tuff subunit is exposed along the coastline from the base of Green Peak to the south headland of Discharge Cove, and is structurally repeated at the north headland of Discharge Cove. The resistant tuff subunit-may be structurally repeated at Crowbar Hill, though these exposures may also represent a second, later episode of tuff deposition.
The subunit includes multiple 15- to 45-meter-thick intervals of bedded and massive, well lithified, zeolotized tuff that forms prominent headlands, steep cliff faces, and sea stacks. These tuff deposits are intercalated with intervals of thinly bedded and laminated fine-grained sandstone and mudstone that differentially erode to form narrow surge channels at the coast. The massive tuff facies is most common and includes chaotic and unstratified deposits with basal scour features, rip-up blocks of shale and tuff, and evidence for soft-sediment deformation (indicating gravity flow transport).
The bedded tuff facies includes packages of planar bedding continuous over tens of feet- with weakly expressed textural grading and no large clasts or evidence for syn-depositional deformation (indicating suspension settlement).
The intervals of laminated and thinly bedded sandstone and mudstone within the subunit of resistant tuff include common layers of tephra and are probably turbidite deposits, suggesting a deep marine depositional.environment for the entire resistant tuff subunit.The fine-grained sandstone and mudstone subunit is exposed along the coastline from the south headland of Discharge Cove to south of Crowbar Hill and is probably structurally repeated north of Crowbar Hill. This fine-grained subunit is a greater than 100 meter thick section of regularly bedded sandstone with minor shale and mudstone that coarsens gradually up-section.
Bedding is laterally continuous over tens of feet, but packages of bedding are difficult to correlate between exposures in different shoreline coves and across Tertiary faults and folds, suggesting that there are significant lateral variations in the subunit. Along the coastline, lithologies include a basal interbedded shale and calcareous sandstone that overlies the resistant tuff subunit and grades up-section into laminated fine-grained saridstone and then into coarsely bedded medium- to coarse-grained sandstone.
A package of diatomaceous sandstone has been recognized within the fine-grained subunit in the DCPP area of Diablo Canyon (PG&E, 2002), but only a small exposure of this lithology was found exposed in the sea cliffs south of Crowbar Hill. The well-bedded and generally coarsening-upward trend in the subunit records progradation of clastic sediments and filling of a distal marine basin during a period of local volcanic quiescence.
The diabase subunit has intruded into the resistant tuff subunit along approximately one kilometer of coastline south of DCPP, consistent with the onshore mapping by Hall (1973a) and PG&E (1988; 1991) that documented the subunit along the base of Green Peak. This dike/sill complex is also mapped on the modem wave-cut platform in the intertidal zone directly south of the breakwater at Intake Cove. Diabase was also identified north of Crowbar Hill where it is exposed as dikes and bedding-parallel sills within the fine-grained subunit. This exposure is a continuation of the diabase body mapped by Hall (1973a) and PG&E (1988; 1991) on the north side of Diablo Canyon. Texture of the diabase varies from aphanitic rock to phaneritic matrix with plagioclase porphyry up to 3 centimeters in diameter, Emplacement of the diabase may have begun coincident with the volcanism that produced the resistant tuff subunit and/or it may have intruded after deposition of the fine-grained subunit.As imaged in the offshore MBES bathymetric data, the Obispo Formation is characterized by distinct and continuous beds that off-lap basement rock on the Santa Rosa Reef shelf southwest Shoreline Fault Zone Report, Appendix B Geology Page B-17 of 112 of San Luis Hill. Portions of this section appear more resistant to erosion, have higher seafloor relief, and are probably composed of the resistant tuff subunit. The well-bedded part is inferred to be the fine-grained subunit. However, in the area far offshore the few diver samples collected are insufficient to differentiate lithology, so the subunits are lumped together as undifferentiated Obispo Formation.
Similarly, in San Luis Obispo Bay, much of the Obispo Formation on the sea floor is inferred to be either the resistant tuff subunit or the fine-grained subunit. Closer to the coastline, the geologic relationships observed onshore are extrapolated to offshore and the subunits are mapped based on the resistant texture of the resistant tuff subunit, the bedded habit of the fine-grained subunit, and the smooth, hummocky texture of the diabase subunit.4.2.3 Monterey Formation The Monterey Formation occurs onshore and offshore in the study area (Plates B-IA to B-ID).It overlies the Obispo Formation and is a roughly 600-meter-thick section of bedded dolomitic siltstone, diatomite, and cherty shale where it is exposed along the coast between Crowbar Hill and south of Coon Creek at Point Buchon (Hall, 1973a; Schwalbach and Bohacs, 1995). The Monterey Formation is thinly bedded and bedding packages are continuous over several tens of feet. The lower half of the Monterey section at Point Buchon records a gradual decrease in clastic deposits (dolomitic siltstone, similar to the fine-grained subunit of the Obispo Formation) and an increase in siliceous shale and porcelaneous chert. This trend reverses in the upper halfof the Monterey section where the proportion of clastic strata increases gradually toward the basal unconformity at the base of the overlying Pismo Formation.
The depositional environment for the Monterey Formation is deep marine, probably lower slope to distal basin (Schwalbach and Bohacs, 1995). Age dating analyses indicate an age of 11.4 to 10.5 Ma for the middle of the section at Point Buchon (Schwalbach and Bohacs, 1995).Offshore exposures of the Monterey Formation were interpreted from MBES bathymetric data (Plate B-lA) assisted by projecting the strike of prominent bedding and the basal contact mapped onshore by Hall (1973a; 1973b) south of Point Buchon and west of the town of Pismo Beach.The basal contact of the Monterey Formation was mapped onthe Santa Rosa Reef shelf by selecting a stratigraphic position that roughly divides bathymetric texture representing the Obispo Formation (thicker, less regular beds with intervals of resistant tuff) with texture representing the Monterey Formation (thinner, regular or rhythmically bedded layers with no resistant interbeds).
The accuracy of this contact along the Santa Rosa Reef shelf is assumed to be within 10 to 15 meters of stratigraphic section in part because the diver and drop core samples near this contact were generally non-diagnostic and of little use in further constraining the contact location.
Both the lower Monterey Formation and the upper Obispo Formation (subunit Tmof) include significant proportions of dolomitic sandstone and mudstone, but only the Monterey includes the unique lithology of chert or porcelaneous shale.4.2.4 Pismo Formation The Pismo Formation overlies the Monterey Formation and at the north end of the Irish Hills is an approximately 600-meter-thick section of marine sandstone and siltstone (Plates B-1A to B-ID) that includes five different members (Hall and Surdam, 1967; Hall, 1973a; 1973b, and Hall et al., 1979). The lower portion of the Pismo Formation includes the Miguelito and Edna Members, which interfinger and roughly define the extent of a Miocene-Pliocene subbasin that occupied the area of Irish Hills east to near Arroyo Grande. The Miguelito Member consists of basinal mudstone and diatomite, and the Edna Member consists of inner shelf sandstone (Stanley Shoreline Fault Zone Report, Appendix B Geology Page B-18 of 112 and Surdham, 1984). The Miguelito Member is exposed along the coastline north of Point Buchon in the south limb of the Pismo syncline and offshore in the Islay Shelf.The upper portion of the Pismo Formation includes the Gragg, Belleview, and Squire Members, all of which have a significantly smaller areal extent than the strata of the lower Pismo Formation and are composed of inner-shelf sandstone and sandy mudstone.
The Gragg and Squire Members have basal unconformities.
The basal portion of the Pismo Formation (Miguelito Member) at Point'Buchon has been dated at about 10.4 to 9.0 Ma, and the upper strata exposed along the coastline to the north was dated at about 6.7 to 6.0 Ma (Keller, 1992; Keller and Baron, 1993). The base of the Gragg Member was estimated at 4.2 Ma by Stanley and Surdham (1984) through correlation to the global sea-level record, and the base of the Squire was similarly estimated at 3.8 Ma. Initial results of microfossil analysis of the Squire Member for our investigations indicate deposition at about 3.0 to 3.3 Ma (PaleoResource Consultants, Inc, personal communication, 2010).No strata were recognized that would correlate with the Pismo Formation in the Santa Rosa Reef shelf, but a small section of the Miguelito Member strata is inferred to form the core of a syncline on the east side of San Luis Bay. Squire Member deposits directly overlie basement rock south of the San Miguelito fault northwest and north of San Luis Hill and in the sea cliff west of the town of Avila Beach. The Squire Member was also identified overlying basement rock in cores described from the Union Oil pier in San Luis Obispo Bay (PG&E, 1990), but is not evident on the flanks of San Luis Hill or offshore to the south or west of San Luis Hill.Similarly to the Monterey Formation, the Pismo Formation was mapped in the offshore using MBES bathymetric images assisted by projecting along clear bedding trends the basal contacts as mapped onshore by Hall (1973a; 1973b) south of Point Buchon and west of the town of Pismo Beach.4.3 Quaternary Stratigraphy The major Quaternary deposits are included on the geologic map (Plates B-lA to B-1D): marine terrace and overlying deposits, alluvium, landslides, and marine sediments.
4.3.1 Onshore deposits associated with marine terraces The onshore marine terraces (Figure B-3-6) (Qm) are described by Hanson et al. (1994).Between Morro Bay and Avila Beach, Hanson et al. (1994) map remnants of at least 12 marine terraces ranging from sea level to 247 meters elevation.
The terraces generally consist of a wAve-cut platform veneered by thin (1 to 2 meters) marine sand and gravel overlain by up to 30 meters of alluvium, alluvial fan deposits, colluvium, and eolian sand. The two lowest terraces of Hanson et al. (1994) are nearly continuous along the coast: the Q, terrace is correlated to Marine Isotope Stage 5a that formed about 80,000 years ago, and the Q2 terrace is correlated with Marine Isotope Stage 5e that formed during the last interglacial interval about 120,000 years ago.For additional discussion of the terrace sequence, see Hanson et al. (1994) and Appendix I.4.3.2 Eolian sand Eolian sand deposits (Qe) in the form of dunes occurs on the northwestern end of the Irish Hills.These consist of reworked beach sands blown inland and deposited onshore as dunes behind the sand spit and beach north of Hazard Canyon as well as plastered on the hills facing the coast Shoreline Fault Zone Report, Appendix B Geology Page B-1 9 of 112 southeast of Estero Bay. The sand dunes are late Pleistocene and Holocene in age and are described in more detail by Wiegers (2009).4.33 Beach deposits Beach deposits occur along the coast of the Irish Hills but are not shown on the geologic map because they are too narrow. They consist of modern beach sands at the south end of Morro Bay and at the small beach at Islay Creek. To the south of Islay Creek the beach deposits are confined to the base of the sea cliffs and consist of rounded gravel, cobbles and boulders, locally sandy, concentrated in coves between headlands.
More extensive beach sands are present at Avila Beach and at Pismo Beach in the southeast part of the study area.4.3.4 Offshore marine deposits The offshore marine deposits (Qs) are known from the drop cores taken during the LTSP. The thickness of these deposits is locally constrained by the high-resolution seismic-reflection profiles.
They consist of sand and silty sand with minor gravel deposits that become finer grained progressively offshore.
Thin dune-like sand sheets (Qsw) cover parts of the sea floor.Evidence for their mobile, ephemeral nature is discussed in Section 3.2 and shown in Figure B-3-5. At the base of the marine sand and silt, a gravel-cobble lag is inferred to overlie the top of bedrock. Paleo-beach deposits and talus or cliff-fall debris are interpreted from the MBES bathymetric images below submerged paleosea cliffs, particularly where they are concentrated along the leeward south and southeast sides of the cliffs.5. STRUCTURE The Shoreline fault zone study area is within the San Luis/Pismo structural block as described by Lettis et al., (1994; 2004). This block is bordered by three active fault zones: the Hosgri, Los Osos and Southwestern Boundary fault zones (including the San Luis Bay fault) (Figure B-4-1).The Hosgri fault zone borders the west side of the study area and separates the Islay and Santa Rosa Reef shelves from the outer continental shelf. The marine bedrock platform and geologic structures are truncated by the Hosgri fault zone (Plates B-lA to B-IC). The south- to southwest-dipping Los Osos fault is on the north and northeast side of the Irish Hills (Lettis and Hall, 1994). The Southwestern Boundary fault zone consists of the north-dipping San Luis Bay fault zone (which in turn includes the Olson and Rattlesnake faults) and the widely spaced Wilmar Avenue, Pecho, Los Berros, and Oceano faults (PG&E, 1988; Lettis et al., 1994). The Wilmar Avenue, Los Berros, and Oceano faults project offshore into San Luis Obispo Bay in the southeastern part of the Shoreline fault zone study area (Plate B-ID). Within these bounding faults are folds and fault zones that record one or more episodes of deformation since the Jurassic (Plates B-lA to B-1D; Figure B-4-1).5.1 Tectonic History The regional tectonic history includes several distinct tectonic events that are recorded in the geology of the study area. A recognition of the regional tectonic history helps put the faulting observed in the Shoreline fault zone study area in context; much of the structural fabric and faulting is inherited from one or more past episodes of deformation, and is not active in the Shoreline Fault Zone Report, Appendix B Geology Page B-20 of 112 0 current tectonic regime. On the other hand, faults that are currently active are probably, at least in part, reactivating older faults that formed under a different tectonic regime. In addition, ancestral faults and structures formed during a prior deformational episode have the potential to be offset markers where they cross currently active faults.The earliest recorded tectonic event in the study area is the coast-parallel subduction that lasted during the Mesozoic and early Cenozoic and produced the chaotic Franciscan Complex (Atwater, 1970; 1998). This episode juxtaposed Jurassic ophiolite (including pillow basalt), various rock bodies within the Franciscan Complex (including serpentinite), and small to large blocks of Cretaceous sandstone within the study area. Localized deformation' produced sheared zones of melange and an overall highly anisotropic rock mass, and all pre-Tertiary rock boundaries are marked by melange or narrower fault zones.As the transform Pacific-North America plate boundary was established in central California in the Miocene, coast-parallel subduction was replaced by west-northwest-directed transtensional deformation (McCulloch, 1987). This episode of deformation is associated with the main Miocene depositional basins of the Obispo, Monterey, and lower Pismo Formations.
Faults within the study area probably included basin-bounding or intra-basin normal, normal-oblique, and strike-slip faults, many of which may have reactivated pre-existing faults related to subduction.
It is probable that the San Miguelito, Edna, and Hosgri were active basin-bounding normal faults at this time.About 8 million years ago,the direction of relative Pacific-North America plate motion changed from west-northwest to about N37&deg;W (Atwater and Stock, 1988). Later, about 5 million years ago, the major Pacific-North America plate boundary fault system stepped east and gradually initiated capture of Baja California and central coastal Californiawithin the Pacific Plate. Some time at or since about 5 million years ago, regional deformation switched from transtension to more coast-parallel strike-slip to transpression.
A regional change to transpression in the middle to late Pliocene is recognized throughout coastal California (e.g.,. Page et al., 1998; Ducea et al., 2003) and may correlate with the progressive eastward development of the Pacific-North America plate boundary.
In the study area, the transpressional deformation episode is associated with Tertiary unconformities, contractional folding of Tertiary strata including the Pismo syncline, and probably inversion of the formerly normal San Miguelito, Edna, and Hosgri faults as reverse, oblique, or strike-slip faults. Offshore mapping with MBES bathymetry and high-resolution seismic-reflection profile data clearly reveal folded and faulted Tertiary strata consistent with this episode of deformation (Plates B-1A to B-ID). The deformation also warps and folds pre-existing fault contacts or angular unconformities that separate the Tertiary section from the underlying Cretaceous basement section.The most recent episode of deformation in the study area is characterized by near-uniform block uplift of the San Luis/Pismo block relative to adjacent blocks in the larger Los Osos/Santa Maria tectonic domain (PG&E, 1988; Lettis et al., 1994; 2004). The block uplift mode of deformation is recorded by flights of Pleistocene marine terraces along the flanks of the Irish Hills (Hanson et al., 1994) that demonstrate the mode of a coherently uplifting block over the.past half-million years or more rather than tilting or folding as recorded in-the Tertiary rocks. The estimated timing of the transition from folding-thrusting-dominated deformation to block uplift is broadly defined to between about 2 and 0.5 million years ago (Hanson et al., 1994).Shoreline Fault Zone Report, Appendix B Geology Page B-21 of 112 5.2 Basement Structures Deformation of Mesozoic and early Tertiary Formations 
-The Franciscan Complex basement rock in the Shoreline fault zone study area is a composite terrain with a high degree of structural and stratigraphic complexity.
Faults within the Franciscan Complex are generally difficult to follow along strike but in outcrop are clearly recognizable as zones of intense localized shearing that separate different Franciscan lithologies.
Deformation is generally localized and pervasive within zones of sheared claystone onshore and in the melange offshore and is less penetrative in sandstone and greenstone rocks away from these melange zones.The Franciscan Complex rocks were faulted against overlying Cretaceous sandstone during one or more subsequent episodes of deformation during the early Tertiary (Wahl, 1995). The faulted contacts between the Franciscan Complex and separate blocks of Cretaceous sandstone onshore are generally narrow in outcrop, commonly less than a few meters wide. Offshore on the Santa ,Rosa Reef shelf, however, the sheared rock forms wide bands of mdlange that separate large bodies of Cretaceous sandstone (Figure B-4-4).Two northwest-striking faults interpreted to be in melange displace broad outcrops of Cretaceous sandstone offshore (Figure B-4-4 and Plate B-IC). The westernmost is 3.4 kilometers west of Point San Luis and strikes N48&deg;W. A strand of this fault may displace a paleo-stream channel right laterally about 80 meters; however, the data also allow the offset to be a bend in the channel and hence be erosional.
The other fault is the South Segment of the Shoreline fault discussed in Section 5.4.3.2.5.3 Tertiary Structures Tertiary bedrock faults and folds commonly truncate or repeat stratigraphic section exposed along the coastline and are clearly imaged offshore in the MBES bathymetric data. The Tertiary strata record unconformities between formations and different styles of folding and faulting that represent one or more episodes of deformation.
Within the study area, map relations suggest that structures vary from one formation to the next. Alternative interpretations of this are: (1) the structures record different tectonic episodes in the Tertiary, (2) the structures record different strain responses of the different rheologies, or (3) different structures formed in different locations within the map area due to differential movement of deeper crustal faults.5.3.1 Deformation of the Tertiary/basement contact Faulting and folding deform the basal contact between basement rocks and the overlying Tertiary strata. The base of the Tertiary section is probably late Oligocene to early Miocene, based on regional age estimates for the Rincon and Vaqueros Formations (Hall, 1973b). This basal contact records a broad-scale deformation evident in its outcrop pattern on the Santa Rosa Reef shelf and onshore (Plates B-1B and B-1C; Figure B-4-1). The northeast end of the contact west of DCPP is inferred from an interpretation of Tertiary rocks exposed through the mobile sand sheets and by seismic-reflection profile data that indicate a contact at depth between basement and bedded Tertiary rocks.5.3.2 Deformation within the Obisno Formation Shoreline Fault Zone Report, Appendix B Geology Page B-22 of 112 Coastline exposures of the Obispo Formation record several forms of syn- and post-depositional deformation.
Syn-depositional deformation is recorded by the disruption of fine-grained intervals within the resistant subunit of the Obispo Formation and incorporation of these lithologies into the chaotic packages of tuff. There is also some evidence for post-depositional slumping.
Post-depositional faulting of the Obispo Formation in the coastline exposures includes at least three different fault sets with clear cross-cutting relationships.
The oldest post-depositional deformation in the coastline exposures of Obispo Formation is a narrow zone of northeast-southwest-oriented faults that places the fine-grained subunit of the Obispo Formation against the resistant subunit at the south end of the Discharge Cove at DCPP (Plate B-1B; Figure B-5-1). This fault zone dips steeply southeast, has a reverse-sinistral sense of displacement, and is cross-cut by one or both of the adjacent east-west and approximately north-south bedrock fault systems described in the following paragraphs.
Bedrock faults striking about north-south displace an intrusive contact between the resistant subunit and the diabase subunit of the Obispo Formation exposed along the south breakwater at Intake Cove at DCPP (Plate B-1B; Figure B-5-1). A section of distinctive beds within the resistant Obispo subunit adjacent to the subunit contact is systematically displaced in a right-lateral sense several hundred feet along two faults in Intake Cove. Two additional north-south oriented faults separate resistant subunit strata on the west from fine-grained subunit strata on the east: one of these faults is at the northwest headland of Discharge Cove, and the other is about 300 meters southeast of Crowbar Hill and projects south to the east side of Lion Rock (Figure B-5-1). The sense of displacement along these north-south faults is dextral with no indication of the amount of vertical displacement.
The north-south fault that crosses the northwest headland of Discharge Cove may continue for about 1.5 kilometers farther south, as suggested by an apparent right-lateral separation of two magnetic lineaments in the enhancement shown in Figure B-5-1. If so, this older right-lateral fault crosses the Shoreline fault and provides a limit to the total right-lateral displacement on the younger fault (described below with the Shoreline fault zone in Section 5.4.3.2).East-west-striking faults in Discharge Cove and the next cove north truncate at least some of the faults that strike approximately north-south (Figure B75-1). The sub-vertical east-west fault in Discharge Cove is observed in the sea cliff where it separates a sliver of resistant Obispo from fine-grained Obispo Formation.
A northwest-southeast-striking fault that juxtaposes Obispo subunits at the south end of Discharge Cove projects northwest to the east bank of Diablo Creek.The lack of a similar fault near the mouth of Diablo Creek supports the interpretation that the northwest-striking fault is truncated by the east-west fault. In another example, the sub-vertical east-west fault in the cove north of Discharge Cove is clearly visible in the modem wave-cut platform and in the sea cliff where it truncates a fold and juxtaposes fine-grained subunits of the Obispo Formation.
This east-west fault must truncate the north-south fault mapped at the northwest headland of Discharge Cove as this north-south fault is absent on the opposite side of the cove to the north.Deformation of the Obispo Formation in the Santa Rosa Reef shelf (Plates B-1B and B-IC)includes small displacements (less than 3 meters) visible in the MBES bathymetric data along generally N20&deg;W to N30&deg;W striking faults. Folds in the Santa Rosa Reef shelf include the large-scale folds that deform the basal Tertiary contact and several other smaller-scale east-west oriented parasitic folds. Deformation of the Obispo Formation evident in the Islay shelf (Plate B-lA) includes several short, discontinuous, roughly east-west-oriented lineaments and faults Shoreline Fault Zone Report, Appendix B Geology Page B-23 of 112 that appear to terminate at the N40W fault (described in Section 5.4.2). Folding of the Obispo Formation in the Islay shelf is tight but mapabl~e at a detailed scale from coastline exposures.
However, this same folding is weakly expressed in the offshore MBES bathymetric data, probably because of the tight folding combined with extensive and complicated intrusion of diabase. Deformation of the Obispo Formation in San Luis Obispo Bay includes some east-west-oriented folding defined by MBES bathymetric data offshore similar to those in coastline exposures (Hall, 1973b). A series of discontinuous east-west-oriented lineaments in the Obispo Formation south of the town of Avila Beach may represent faults, joint discontinuities, or the dominant orientation of resistant beds within the Obispo Formation.
5.3.3 Deformation within the Monterey Formation Late Tertiary deformation of the Monterey Formation has been primarily accommodated through folding, rather than through the brittle faulting that characterizes most of the deformation of the Obispo Formation.
In the Islay shelf the Monterey Formation forms a moderately dipping homocline with abundant small, parasitic folds (Plate B-1A) such as the minor doubly-plunging syncline imaged in the MBES bathymetric data that appears to correlate with a small syncline mapped onshore near Point Buchon by Hall et al. (1979). Faults within the Monterey Formation appear to be caused by bedding-parallel shearing and drag folding within tight folds, and offset.equivalents are difficult to identify.
In the Santa Rosa Reef shelf the east-west folds recognized in the Obispo Formation generally continue east into the Monterey Formation.
In one case, folding along the approximate Obispo-Monterey contact has been rotated into a northwest-southeast orientation by drag folding along a strand of the Hosgri fault zone (Plate B-i C).Deformation of the Monterey Formation in San Luis Obispo Bay includes the same approximately east-west-oriented folding described above in the Obispo Formation.
5.3.4 Deformation within the Pismo Formation The Pismo syncline is a major structure that underlies the crest of the Irish Hills and plunges northwest toward the coast. At and southeast of the coastline, the Miguelito Member of the Pismo Formation is at the core of the syncline.
In the Islay shelf along the northwest projection of the syncline axis, folds and faults are imaged on the MBES bathymetric data with growing complexity but are clearly correlative to folds mapped at the coastline (Plate B-1A). Bedding attitudes in the northern portion of the Islay shelf define a broad, northwest-plunging antiform that marks the end of the Pismo syncline and perhaps results from deformation related to the nearby Hosgri or Los Osos fault zones in southern Estero Bay.Although folds, faults and fractures in the Pismo Formation are less pronounced than in the underlying Obispo and Monterey formations, they are clearly observed on the Islay shelf. Folds in thePismo Formation strike N60&deg;W to N70&deg;W and associated with the folds are short faults that lie along and parallel to the fold axes. Other short faults striking N50 0 W slightly displace bedding. The largest fault zone in the Pismo strata lies-northwest of the mouth of Islay Creek.This prominent fault zone strikes N25&deg;W and trends onshore at the mouth of Islay Creek where Hall et al. (1979) maps a small anticline.
Offshore it extends about 5.5 kilometers ending in a syncline.
The 300-meter-wide fault zone appears to offset Pismo strata with possible right-lateral separation.
The fault projection onshore does not deform the youngest emergent strandlines, associated with the 80,000- and the 120,000-year-old sea-level highstands (Hanson et al., 1994).Shoreline Fault Zone Report, Appendix B Geology Page B-24 of 112 The LTSP analysis identified a group of northwest striking faults in the offshore that were collectively called the Crowbar faults (PG&E, 1988). In the analysis of the MBES bathymetric data and the high-resolution seismic-reflection profiles, a series of small, northwesterly striking faults associated with the folds were identified.
These structures are more westerly striking than those mapped as the Crowbar faults in 1988. Most of these small faults are associated with the northwest folding in Monterey and Pismo Formation strata (Figure B-5-2) and are not the through-going, more northerly Crowbar faults extending between the coast and the Hosgri fault, zone as interpreted in the LTSP. It appears that the LTSP-interpreted extension of faults between the widely spaced older seismic-reflection profiles crossed structures visible in the MBES bathymetric data.5.4 Quaternary Structures 5.4.1 Hosgri fault zone The Hosgri fault zone is an active transpressional right-slip fault zone that extends southeastward approximately 110 kilometers from 6 kilometers offshore Cambria in the north to a point 5 kilometers northwest of Point Pedernales in the south (Hanson et al., 2004). The fault zone lies offshore for its total length and separates two tectonic domains with contrasting styles of crustal deformation.
These domains are the offshore Santa Maria Basin on the western side of the fault zone and the onshore Los Osos domain on the eastern side (PG&E, 1988; 1990; Lettis et al., 2004).The Hosgri fault zone was mapped along its entire length using petroleum industry multichannel seismic-reflection profile data that imaged the fault planes to depths of 1.5 to 3 kilometers beneath the sea floor (PG&E, 1988; 1990). Part of the fault zone has been re-mapped for this study using the USGS single channel, high-resolution seismic-reflection profile data (Appendix H). The USGS data set provides improved near-surface resolution of the fault traces and associated structures but with limited depth penetration.
The surface traces of the fault zone for an approximate 33-km long section are shown on three sheets of the geological map, Plates B-1A to B- IC, but the fault zone' extends both northwest and southeast out of the Shoreline fault zone study area.In the study area the fault zone strikes N25&deg;W-N30&deg;W and consists of many separate subparallel and en-echelon strands. It generally controls the shelf break and truncates many geologic structures east of the fault. With the exception of a few rock outcrops and changes in sea-floor slope, the fault zone has little surface expression.
The fault zone appears to form a seaward limit to the Santa Rosa Reef and Islay shelves, restricting the sea-floor outcrops to the near-shore part of the continental shelf.As mapped from the high-resolution seismic-reflection data, the Hosgri fault zone consists of multiple traces that are continuous for as long as 18 kilometers.
The fault zone is 1- to 2.5-kilometers wide and contains strands that appear to extend to the sea floor and strands that are buried by sediment.
Within the fault zone are several associated en-echelon faults and folds. On the relatively high-resolution seismic-reflection profiles the faults appear vertical to steeply dipping in the upper few hundreds of meters. On the common-depth point exploration seismic-Shoreline Fault Zone Report, Appendix B Geology Page B-25 of 112 reflection profiles with several seconds of signal penetration some of the faults dip steeply to the east within the upper I to 2 kilometers of Tertiary and pre-Tertiary rock (PG&E, 1988).South of Estero Bay the Hosgri fault zone has three traces, A2, C, and CI (Plate B-1A). The average strike is about N22&deg;W. Trace A2 is buried, whereas both traces C and C1 appear to extend to the seafloor.
Trace Cl is less than 7 kilometers long. Trace C extends south of Point Buchon where five other traces, A, Al, A2, B, and C2, are mapped (Plate B-1B). Southwest of DCPP the average strike changes from N22&deg;W to N35&deg;W to N40 W. Trace A is exposed at the seafloor over most of its length and associated with bedrock outcrops (probably Monterey Formation).
The northern kilometer of trace A, most of trace Al, and traces A2 and B are buried. Trace C is exposed at the seafloor for. all but its southern 2 kilometers.
Trace C2 overlaps the southern 4 kilometers of trace C and is exposed at the seafloor for most of its length.Seafloor outcrops of the Monterey Formation are seen at several places along the eastern side of trace C2 and locally at the left bend (a restraining bend) between traces C2 and A.West of Point San Luis the Hosgri fault zone has two main traces and several shorter traces between the two main traces, (Plate B-iC). The two main traces are labeled the West and East traces (trace names are taken from the LTSP report, PG&E, 1988). The intermediate traces lie between the East and West traces and are generally buried by several meters of sediment.
The general trend of the West and East traces is about N25 W. The seafloor outcrops along the eastern side of the East trace are mapped as Monterey and Obispo Formations.
There are several folds that locally come to the seafloor in the 2.5-kilometer wide zone between the West and East traces.Offshore (west) and south of DCPP, the Hosgri fault zone has a left restraining bend that is prominently exhibited in the zone's two major fault traces (Hosgri West and Hosgri East, Plate, B-1B). East of this restraining bend, folds and faults in Tertiary strata also show a major shift in orientation with structural trends becoming more east-west (approximately N70&deg;W) in orientation than those structures to the north. Typically, fold axes bend northward into the Hosgri East trace or are truncated by the fault.Comparison with LTSP maps -Maps showing bathymetry, seafloor sediment thickness and geologic structural trends were prepared for the LTSP (PG&E, 1988; 1990). These maps were also at a scale of 1:12,000 and showed similar features and interpretations to those shown on Plates B-lA to B-IC. Although the LTSP maps used different projections and datums, the differences are very minor at this scale. The LTSP maps were based on single-beam echo sounder, side-scan sonar, high-resolution seismic reflection, and multichannel CDP exploration seismic-reflection data sets. In general the older survey tracklines did not approach as close to shore as the high-resolution seismic-reflection survey lines and the data were not in digital formats, making mapping a labor-intensive drafting effort.A cursory comparison of the LTSP maps with Plates B-lA to B-IC was made by overlaying the former interpretations over those produced from the 2008 MBES bathymetry and high-resolution seismic-reflection data sets. Locations of the Hosgri Fault traces are in good agreement (generally within 5 to 10 meters) between the 1988 exploration and 2008-2009 seismic-reflection data sets, although the deeper data from the earlier surveys suggests a buried westerly trace not seen in the 2008 near-surface high-resolution profiles.
The major differences are listed below for the individual plates.Shoreline Fault Zone Report, Appendix B Geology Page B-26 of 112 On Plate B-1A, the major differences between the LTSP mapping and the new mapping are in the area'east of the Hosgri fault zone (Plate B-1A and Figure B-5-2). The LTSP mapping of the"Crowbar faults" and offshore extension of the Los Osos fault zone are not imaged by the MBES bathymeiric data. Although there are folds and short, older, bedrock faults in the area where the Crowbar faults were mapped, the through-going faults extending from the shoreline to the Hosgri fault zone are not seen, in the upper rock units in the high-resolution seismic-reflection and MBES bathymetry data sets. The previously mapped area of the Los Osos fault zone appears to contain zones of continuous uninterrupted bedding outcrops as well as smaller structures trending across at angles to the previously mapped fault zone. A surface feature mapped as a fault on the 2008 high-resolution seismic-reflection profiles trends parallel to the former Los Osos fault trace, but lies about 1.5 kilometers to the northeast.
As on Plate B-1A, the locations of the traces of the Hosgri fault zone on Plate B-1B are in good agreement between the LTSP'study and the traces imaged on the 2008 high-resolution seismic-reflection profiles.
However, the earlier surveys did not approach close enough to the shoreline to map any of the lineaments that may be associated with the Shoreline fault zone. In addition, the Pecho fault mapped from the LTSP data (PG&E, 1988) intersects the Hosgri fault zone in the southern part of this plate. The 2008 MBES bathymetry and high-resolution seismic-reflection data do not clearly define a through-going Pecho fault in this area, suggesting it may be a blind fault.On Plate B- IC, the traces of the Hosgri fault zone based on the 2008 high-resolution seismic-reflection profiles generally agree with the mapping based on the LTSP data (PG&E, 1988).Similar to the area farther north, the LTSP data provided little information regarding the details of the near-shore area including the Shoreline fault zone. Also, the southeastward extension of the Pecho fault cannot be confirmed in the MBES bathymetry or high-resolution seismic-reflection data.5.4.2 N40W fault The N40W fault parallels the coast 1 to 1 1/2 kilometers offshore north from Lion Rock and to the west of Point Buchon (Plate B-1A). Its characteristics are summarized in Table B-4 and described below.The N40W fault is about 5 to 7 kilometers long and generally strikes about N40&deg;W (N35 0 to 44 0 W). The fault cuts the Obispo, Monterey and Pismo Formations.
It is expressed in the north by sharp linear truncations of rock strata in contact with the mobile sand sheets to the west.Based on its linearity, the N40W fault is assumed to be a steeply dipping to vertical fault. The N40W fault, and its northwestward projection, is crossed by a few deep Comap seismic-reflection profiles (Figure B-5-3) and several 2008 high-resolution seismic-reflection profiles (Appendix H). In general the images of the structures (folds and-faults) on the eastern side of the Hosgri fault zone are better on the Comap profiles than the high-resolution profiles.
Comap profile CM-21 and several 2008 high-resolution profiles show little coherence of reflectors across the N40W fault and thus provide little information about fault dip, structural characteristics, or estimated cumulative offset. The north end of the fault is determined based on the northwestern extent of the abrupt linear truncation of rock and the apparent absence of faulting in the Comap profile CM-23 (Figure B-5-3).Comparison of the current map with the LTSP map (PG&E, 1988) for the northern portion of the N40W fault is shown in Figure B-5-2. The northern part of the N40W fault shown in this Shoreline Fault Zone Report, Appendix B Geology Page B-27 of 112 Appendix is located along several traces of the more west-northwest-trending Crowbar faults than shown in the LTSP interpretation.
The latter interpretations were based not only on the Comap data, but also on more closely spaced lines from the analog Aquatronics and BBN surveys. In areas covered by the MBES bathymetric data the structural trends are clear.West of Crowbar Hill, the N40W fault juxtaposes contrasting sedimentary units in the Obispo Formation (Figure B-5-4). The southern end is interpreted to continue beneath a sand sheet for approximately 2 kilometers along a steep magnetic gradient (Appendix D) and end west of Lion Rock (Plate B-1B). The magnetic anomaly that crosses the N40W fault at a low angle is interpreted to be an Obispo diabase dike, but the N40W fault itself does not appear to have a magnetic anomaly associated with it. At its southern end, the N40W fault projects beneath a mobile sand sheet toward the Central segment (C-1) of the Shoreline fault zone with a 25 degree difference in strike. Based on the available data, the structural relationship between the Central segment and the N40W fault is unclear.The N40W fault is crossed by, a wave-cut platform that corresponds to the paleostrandline at 38 meters depth (Figure B-5-4). This platform is estimated to be approximately 49,000 to 60,000 years old (marine oxygen-isotope stage (MIS) 3) or older (Appendix I). Considering multiple bathymetric profiles across the fault and the natural variability of the wave-cut platform, the estimated vertical separation across the N40W fault is zero with a combined uncertainty of approximately 2 meters (Appendix I, Section 7.3.1). The limited amount of vertical deformation is similar to that observed on the Central segment of the Shoreline fault zone (discussed below in Section 5.4.3.5).5.4.3 Shoreline fault zone The Quaternary structural aspects of the Shoreline fault zone have been identified and characterized through an extensive program of onshore and offshore data acquisitions and analyses that commenced in late 2008 and continued through 2010. Preliminary results were presented in the PG&E (2010) Progress Report. Additional investigations completed since the Progress Report have led to an improved understanding of the Shoreline fault zone, including information on fault location, geometry, segmentation, slip rate, and relationship to the Hosgri fault zone, Southwestern Boundary fault zone, and older Tertiary structures.
The geologic characteristics of the Shoreline fault zone were developed from the following:
: 1. Geologic interpretation of MBES bathymetric imagery;2. Assessment of submerged marine terraces from MBES bathymetric imagery (Appendix I);3. Correlation of geologic units and structures onshore and offshore using a low-tide LiDAR base map (Appendix G);4. Reinterpretation of offshore diver and core samples from the LTSP and collection of 50 additional offshore samples (Tables B-i to B-3);5. Interpretation of high-resolution seismic-reflection profiles acquired in 2008 and 2009.(Appendix H), and seismic-reflection profiles from the LTSP (PG&E, 1988); and 6. Analysis of magnetic field data from helicopter and ship-borne measurements (Appendix D).Shoreline Fault Zone Report, Appendix B Geology Page B-28 of 112 This section describes the location, length, faulting style, dip, recency of activity, slip rate, and relationship of the Shoreline fault zone to other faults in the region. Characteristics of individual segments of the fault are summarized in Table B-5 for the North segment, Table B-6 for the Central segment, and Table B-7 for the South segment., Alternative interpretations and uncertainties in the fault characteristics are explicitly addressed to provide a clear rationale for seismic source characterization.
Several comparative maps illustrate the interpretations of geology and submerged marine terraces with the MBES bathymetric imagery along the Central and South segments of the Shoreline fault zone at key locations along the fault zone at 1:12,000 scale. These comparative maps highlight the following areas: (1) west of Lion Rock, (2) directly west of DCPP, (3) directly south of DCPP, (4) southwest of Olson Hill, (5) west of Rattlesnake Creek, and (6) southwest of Point San Luis (Figures B-5 7 4 to B-5-9).5.4.3.1 Location of the Shoreline fault zone and its relationship to older Tertiary structures The Shoreline fault zone appears to involve local reactivation of a pre-existing fault. Although the pre-existing fault is not reflected in the regional gravity data, this older fault is associated with a distinct, linear magnetic anomaly as seen in thehigh-resolution helicopter magnetic field data (Appendix D and Figure B-4-3). The magnetic anomalies associated with the older fault zone between about Olson Hill and offshore Point San Luis probably result from serpentinite or greenstone lenses within Franciscan melange (Plates B-1A to I-C). Juxtaposition of magnetic (e.g., greenstone) against non-magnetic (e.g., sandstone) blocks of pre-Tertiary rock along the older fault zone also likely contribute to the strong signal in the magnetic field anomaly. This juxtaposition of distinct blocks of pre-Tertiary rock and the development of mdlange has its origins in Cretaceous to early Tertiary coast-parallel subduction and development of the Franciscan accretionary wedge complex, and suggests the Shoreline fault zone represents at least local reactivation of an older well-developed fault zone that had significant cumulative displacement during prior episode(s) of deformation.
From a location northwest of Olson Hill to the area directly west of DCPP, the magnetic anomalies are spatially associated with intrusive diabase that is part of the Miocene Obispo Formation on the landward side of the older fault zone, and probable Franciscan Complex greenstone on the seaward side of the older fault zone (Plates B-1A to B-IC). Here, the pre-existing fault juxtaposes Franciscan Complex rocks against the Tertiary Obispo and Monterey Formations, which indicates a prior episode of faulting dating to late Miocene and perhaps Pliocene time. This Tertiary episode of deformation probably occurred either during a regionally recognized mid-Miocene to early Pliocene period of transtensional deformation or during a later middle to late Pliocene period of transpressional deformation (PG&E, 1988 and references therein).
Other structural features in the DCPP area that were active during these regional episodes of deformation include the San Miguelito fault, Pismo syncline, and Edna fault, which originated as extensional faults and basins during the earlier transtensional tectonic regime.These structures were reactivated in a transpressional deformation episode in about the middle Pliocene coincident with reorganization of the Pacific-North America plate boundary (Lettis et al., 2004 and references therein).
Many of these faults have been inactive since I to 2 million years ago when the mode of deformation in the Irish Hills switched from folding to block uplift (Lettis et al., 2004; Lettis and Hanson, 1992).Shoreline Fault Zone Report, Appendix B Geology Page B-29 of 112 More recently, differential erosion along the pre-existing fault zone during periods of lower sea level produced a prominent series of bathymetric lineaments and associated scarps. The probable northern reach of the pre-existing fault zone includes a prominent escarpment off the coast of Point Buchon along the N40W fault (shown on Plate B-1A). The linear magnetic gradient (Figure B-4-3) associated with the N40W fault probably is derived from intrusive Tertiary diabase, as pre-Tertiary basement rocks are not mapped along the coast or in the near-shore bedrock platform north of the DCPP. Based on the linearity of the anomaly, it is likely that the geometry of the diabase is structurally controlled.
The N40W fault is interpreted to cut across the diabase.The central and southern seismicity sub-lineaments align with parts of the pre-existing Tertiary fault (within the half-kilometer location resolution of the seismicity comprising the lineament)(see main report, Plate 1), indicating that the older fault has been locally reactivated in the current stress regime. In particular, the central and southern seismicity sub-lineaments closely align with the pre-existing older Tertiary fault. The Central and South segments of the Shoreline fault zone are thus interpreted to represent reactivation of this part of the older Tertiary fault.Seismicity along the northern sub-lineament trends northwest toward the Hosgri fault zone and lies west of the N40W fault (Figure 4-1). Late Quaternary marine sedimentary and ephemeral dri'fting sand sheets on the seafloor mask existing geomorphic expression of an active fault and any direct observation of youthful geologic structure that may be associated with the seismicity lineament.
The origin of the northern seismicity sub-lineament and direct linkage to a bedrock fault, therefore, is less plausible than for the central and southern seismicity sub-lineaments and the older Tertiary faults. As described in the main report, Section 4.2.4, alternative structural origins of the northern seismicity sub-lineament include: (1) a steeply east-dipping Hosgri fault zone; (2) a sub-vertical fault (buried or emergent) coincident with the seismicity sub-lineament; and (3) the N40W fault, with a steeply west-dipping shallow crustal portion to link the surface trace of the fault with the seismicity trend.Three methods were used to evaluate whether a direct structural geologic link can be made between the Hosgri fault zone and a distinct fault that could be associated with the northern seismicity sub-lineament: 
(1) re-examination of the USGS high-resolution seismic-reflection profiles that cross the northern seismicity sub-lineament to look for evidence of faulting; (2)reprocessing of three of these high-resolution seismic-reflection profiles to improve data resolution; and (3) re-examination of high-energy Comap seismic-reflection profiles interpreted during the LTSP (PG&E, 1990) that cross the northern seismicity sub-lineament and the N40W fault trend. The Progress Report (PG&E, 2010) concluded based on a preliminary examination of the 2008 and 2009 high-resolution sparker data that there was no evidence for a bedrock fault along the northern seismicity sub-lineament.
Re-examination of Comap line (CM-21) collected across the northern end of the seismicity lineament reveals gently folded Tertiary strata east of the Hosgri fault zone with no evidence of faulting across the northern seismicity sub-lineament within the resolution of the seismic-reflection profile (Figure B-5-3). In contrast, this line shows disruptions in reflectors consistent with faulting or tight folding across the nearby N40W fault.Reprocessed high-resolution seismic-reflection profiles (PBS-22, PBS-26, and PBS-296) at the northern and southern ends of the northern seismicity sub-lineament provide significant improvement in overall data clarity compared to the basic processing by the USGS. Although Shoreline Fault Zone Report, Appendix B Geology Page B-30 of 112 the seismic-reflection data are presently insufficient to definitively evaluate the presence or absence of faulting, careful re-examination of the high-resolution profiles crossing the central part of the northern seismicity sub-lineament permits a preliminary interpretation of probable minor vertical separations across sub-vertical faults in Tertiary strata that were plotted on Plates B-lA and B-lB as two concealed, queried, en-echelon faults. The southwestern one follows the axis of a well-expressed syncline in Monterey(?)
strata and the fault to the northeast is sub-parallel.
These faults generally align with the northern seismicity sub-lineament (see main report, Plate 1). Preliminary estimates of vertical separations are on the order of 5 to 10 meters with the northeast side down. Direct correlation of Tertiary strata across the faults also suggests that the amount of cumulative lateral displacement is limited to a few tens of meters or less. These faults clearly lie west of the N40W fault, and are tentatively named the North segment of the Shoreline fault. Given the minor displacement of Tertiary strata, this newly-identified North segment of the Shoreline fault zone does not appear to be reactivating a well-developed older Tertiary fault similar to the Central and South segments of the Shoreline fault zone.Based on the above evidence, the relative merits of the three alternative interpretations of the North segment of the Shoreline fault zone are assessed.
The preferred alternative is that the newly-identified North segment of the Shoreline fault coincides generally with the northern seismicity sub-lineament (Figure B-4-1). The fault either has produced only minor displacement in the Tertiary strata in the near surface (similar to the small faults in the Monterey and Pismo Formation rocks imaged in the MBES bathymetric data), or is "blind" and does not extend to the near-surface.
This location for the fault is preferred because it most closely aligns with the northern seismicity sub-lineament.
The second alternative locates the North fault segment along the N40W fault. This alternative is less preferred because the N40W fault departs from the seismicity lineament, but the alternative does have the advantage of being associated with a recognizable pre-existing fault. The third alternative is that some or all of the northern seismicity sub-lineament is associated with an east-dipping Hosgri fault zone, in which case the North segment of the Shoreline fault does not exist or is limited to a few kilometers in length beyond the better-defined Central segment.5.4.3.2 Length and segments The Shoreline fault zone, including all three segments, has an overall strike of about N60&deg;W and is up to 23 kilometers long (Plates B-lA to B-i C). The total length of individual segments and the continuity and integration of the fault as a whole are discussed below.The North segment is up to 8 kilometers long. The uncertainty in the segment length encompasses the range of alternative locations described in Section 5.4.3.1 of the main report, ranging between zero length (with seismicity occurring on an east-dipping Hosgri fault zone at depth) and the maximum 8 kilometers length extending southeast from the Hosgri fault zone to south of Lion Rock (Table B-5). The alternative N40W fault trace also yields an 8 kilometer segment length (Table B-4). The North segment is at least partially concealed beneath marine sediments and the ephemeral drifting sand sheet on the seafloor and has no geomorphic expression.
The alternative surface trace along the N40W fault coincides with a linear escarpment formed by a composite series of submerged paleostrandlines (Appendix I).The two alternative locations of the North segment have different expressions in the magnetic intensity data (Figure B-4-3). The preferred trace that follows the seismicity sub-lineament does not coincide with a strong magnetic anomaly. The alternative N40W trace is subparallel to but Shoreline Fault Zone Report, Appendix B Geology Page B-31 of 112 crosses a linear magnetic anomaly associated with intrusive diabase (Section 5.4.2). The south ends of the North segment and the N40W fault are obscured by mobile sand sheets so the boundary between the North and Central segments is unclear. However, in this area magnetic anomalies are not continuous and appear complex. This complexity in the magnetic field is interpreted to represent structural complexity that suggests a segment termination and possible structural barrier to rupture.The Central segment is approximately 8 kilometers long and follows an older reactivated Tertiary fault that is well expressed in the geology and as a magnetic anomaly (Plate B-1B;Figure B-4-3; Table B-6). The Central segment is further divided into three geomorphically and structurally defined en-echelon subsegments, C- 1, C-2, and C-3. These subsegments are hot considered to be rupture segments in the seismic source characterization of the Shoreline fault zone. Subsegment C-I connects with C-2 at a change in strike and the boundary between C-2 and C-3 is a right step of 100 to 200 meters. Subsegment C-1 is west of Discharge Cove and its faulting appears to die out northward beneath the sand sheet directly south of Lion Rock. The northern end of C-I does not follow the magnetic anomaly high that characterizes the majority of the Central and South segments but transitions into a magnetic trough. Subsegment C-I forms a prominent and well-defined bathymetric lineament and, where mapped at the seafloor, juxtaposes Tertiary diabase against Franciscan m6lange (Figure B-5-5).Subsegment C-2 also forms a prominent, well-defined bathymetric lineament and juxtaposes Obispo diabase, Cretaceous sandstone and Franciscan m6lange on the east against a thin mobile sand sheet covering Franciscan m6lange on the west (Figures B-5-6 and B-5-7). The sub-segment coincides with a linear peak in the magnetic anomaly data (Figure B-4-3 and B-4-4).West of Olson Hill, a moderate to strong, 900-meter-long geomorphic lineament is evident on the MBES bathymetric image. It lies within a shallow, 2- to 4-meter deep, 25-meter wide trough in Franciscan melange and is likely accentuated by differential erosion (Figure B-5-7). To the south, subsegment C-2 ends near where the Olson Hill deformation zone (considered a part of the San Luis Bay fault zone) projects offshore.
A direct structural or geomorphic linkage between the Central segment of the Shoreline fault zone and the bedrock faults near Olson Hill has not been established (Figure B-5-7). The step-over between subsegments C-2 and C-3 is southeast of Olson Hill where the linear magnetic anomaly high ends.Subsegment C-3 also is expressed as a well-defined bathymetric lineament (Plates B-1B and BIl-C; Figure B-5-8). The lineament is primarily in Cretaceous sandstone and Franciscan m6lange and coincides with a magnetic' anomaly high (Figure B-4-4). As shown on Figure B-5-8, the southern end of subsegment C-3 may bend to the east and follow a lineament (also interpreted to be a paleostrandline) that projects directly toward the Rattlesnake fault (the southern strand of the San Luis Bay fault zone). The apparent connection of the two faults 'suggests that there may be a kinematic link between these two structures (see main report, Section 5.4.4).The South segment is approximately 7 kilometers long and, like the Central segment, follows a reactivated older bedrock fault (Table B-7). It is expressed as a poor to moderate bathymetric lineament inferred to be in a band of m6lange covered by a thin mobile sand sheet. Locally, the South segment truncates bedding in Cretaceous sandstone along a low, northeast-facing escarpment (Plate B-iC; Figuie B-5-9). It is also associated with a strong linear magnetic high (Figure B-4-3). In detail, the fault trace defined on the MBES bathymetric data follows the west flank of the magnetic anomaly high rather than the crest. The northern end of the South segment lies within a broad zone of Franciscan melange that is covered by a mobile sand sheet, so its Shoreline Fault Zone Report, Appendix B Geology Page B-32 of 112 exact location is uncertain.
The junction between the Central and South segments is interpreted as either a right stepover of 100 to 500 meters, or the two segments meeting at the north end of the linear magnetic anomaly southeast of Rattlesnake Creek. The south end of the South Segment projects beneath a mobile sand sheet southwest of Point ,San Luis (Figure B-4-1).5.4.3.3 Faulting style The Shoreline fault zone is inferred to be primarily a right-lateral fault based on earthquake focal-mechanisms, vertical alignment of seismicity, and the linear geologic expression of the fault on the seafloor along the Central and South segments.
However, some focal mechanisms along the North and Central segments show right-oblique or right-reverse motion, and one focal mechanism along the South segment shows right-normal motion. These oblique mechanisms suggest that the fault may accommodate some vertical displacement as well as lateral displacement.
In earthquake rupture scenario models considered in the seismic hazard analysis where the Central and North segments are linked with the San Luis Bay fault zone, the fault zone forms an uplift rate boundary and is considered to have a significant northeast-side up vertical component (see main report, Section 5.1.1).5.4.3.4 Geometry The seismicity defines a nearly vertical seismic source zone and is discussed in the main report, Section 4.2). A vertical fault zone is consistent with the linear geologic and geomorphic expression of the fault on the seafloor along the Central and South segments, but geologic data (including high-resolution seismic-reflection profiles) are lacking to independently measure the dip of the Shoreline fault zone. Local 2D modeling of the helicopter magnetic data across .the Central segment of the Shoreline fault zone shows that magnetic anomalies coincident with the Shoreline fault zone can be explained by a vertical fault in the shallow crust, but the solutions are not unique (Appendix D).5.4.3.5 Evidence of activity This subsegment addresses only the geologic or geomorphic evidence for recency of activity of the Shoreline fault zone; the seismicity lineament as evidence for activity is discussed in the main report (Section 4.2). The Shoreline fault zone lies entirely offshore and thus it is difficult to evaluate its activity with direct evidence.
The MBES bathymetric images were extensively probed to identify geologic or geomorphic features that would record late Quaternary activity.Such features include potentially datable sediments that appeared offset, or geomorphic features such as paleostrandlines, wave-cut platforms, or channels on both sides of the fault zone that could be used to constrain cumulative slip. No geologic or geomorphic features were found that definitively prove or disprove activity of the Shoreline fault zone. Two lines of evidence are available to qualitatively assess the recency of activity of the Shoreline fault zone: (1) the geomorphic expression of the fault zone, and (2) vertical deformation of submerged wave-cut platforms that cross the fault zone.The well-expressed geomorphic scarps along certain sections of the fault zone described in Section 5.4.3.2 are indirect indicators of activity of the fault. These scarps include the southwest-facing fault-line scarps along the Central segment (Figures B-5-5 to B-5-7) and the northeast-facing fault-line scarps along parts of the Southern segment (Plates B-IC and B-1D).Most of the scarps are expressed as a juxtaposition of rock against mobile sand sheets, and in one location (sub-segment C-2) there is a fault-line scarp within bedrock interpreted as m6lange. All Shoreline Fault Zone Report, Appendix B Geology Page B-33 of 112 the scarps are interpreted to result from differential erosion. Their size and locally sharp expression is suggestive of a contrast in erodability of rock on opposite sides of the fault; this sharp expression is probably accentuated by easily eroded fault rock within the fault zone.Additionally, it is reasonable that the existence and linearity of a scarp with vertical separation across it is maintained by cumulative movement on the fault, even if the amount of vertical separation is attributed to both differential erosion and long-term cumulative deformation.
However, with the current lack of detailed understanding of the geology along the scarps, differential erosion alone is sufficient to produce the observed geomorphic expression, and thus the existence and sharpness of the fault-line scarps does not require the fault zone to be active.The second line of evidence available to evaluate activity of the Shoreline fault zone comes from three locations where the Central anad South segments cross late-Quaternary wave-cut platforms, and one location where a correlated paleostrandline is mapped on opposite sides of the South segment. These locations are described in detail in Appendix I, Section 7.3, and are summarized from north to south below: Central segment, subsegment C-2 near intersection with subsegment C In the stepover region between the C-I and C-2 subsegments of the Shoreline fault zone the Shoreline fault zone locally is buried by a mobile sand sheet that is thought to cover a wave-cut platform associated with a -25 meter (in) paleostrandline (Figure B-5-5). Based on its depth, the wave-cut platform is estimated to have developed during MIS 5 or earlier, and hence is older than approximately 75,000 years (Appendix I). Contours of the top-of-rock surface are interpreted from high-resolution seismic-reflection profiles, and an elevation profile across the contours shows a 1 -m-high scarp (with northeast-side up)with a combined uncertainty of 2.5 m (Appendix I, Section 7.3.2). The preferred interpretation is that this scarp is a fault-line scdrp formed by differential erosion that was not completely removed during development of the -25 m wave-cut platform.
The basis for the preferred interpretation is the presence of fault-line scarps northwest and southeast of the -25 m wave-cut platform and the lack of evidence for vertical separation on subsegment C-2 where iticrosses the -21 m wave-cut platform (discussed below).However, we cannot preclude the scarp is vertical separation on the Shoreline fault zone and is caused by late Quaternary, tectonic deformation.
Along strike to the southeast, the Shoreline fault zone appears to follow a sediment-filled trough etched in bedrock, indicating local differential erosion along the fault trace (Figures B-5-5 and B-5-6).Therefore, we conclude that vertical offset on the Shoreline fault zone since approximately 75,000 years is either zero (from the preferred interpretation that the apparent scarp is due to differential erosion) or 1 1 2.5 meters with the center value having a northeast-side up vertical separation (Section 5.4.3.5 and Appendix I, Section 7.3.2). Using the vertical separation and the estimated minimum age of 75,000 years for the wave-cut platform yields a vertical separation rate of 0 or 0.01 +/- 0.03 mm/yr.Central segment, subsegment C-2 -South and southwest of the entrance to DCPP the Shoreline fault zone locally crosses a wave-cut platform associated with a -21 m paleostrandline (Figure B-5-6). Based on its depth, the wave-cut platform is estimated to have developed at least 75,000 years ago (Appendix I). Analysis of elevation profiles across the wave-cut platform suggests there is zero vertical separation across the mapped fault trace with a combined uncertainty of approximately 
+/-1.5 m (Appendix I, Section 7.3.2).Shoreline Fault Zone Report, Appendix B Geology Page B-34 of 112 South segment -South of Point San Luis, the South segment of the Shoreline fault zone locally crosses a wave-cut platform associated with a -31 m paleostrandline (Figure B-5-9). Although the paleostrandline itself is not preserved for approximately 100 meters directly adjacent to the fault zone, sections of the paleostrandline several hundred meters long are mapped on either side of the fault zone and are correlated.
Based on its depth, the wave-cut platform is estimated to have developed at least 75,000 years ago (Appendix I). Analysis of elevation profiles across the wave-cut platform suggests there is zero vertical separation across the mapped fault trace with a combined uncertainty of approximately 
+/- 1.5 m (Appendix I, Section 7.3.3).The results summarized above suggest that there is no strong evidence for activity on the Shoreline fault zone in the last 75,000 years. Although the buried wave-cut platform along the C-I sub-segment has an apparent scarp, a preferred interpretation for this scarp is that it is not due to late Quaternary surface-fault rupture, and the wave-cut platform located approximately 1.3 km to the southeast along the C-2 sub-segment shows no evidence for vertical separation across the fault zone with a lower combined uncertainty.
Given the measurement and geologic context uncertainties in the data, however, we cannot preclude that the approximately 75,000-year-old wave-cut platforms are offset by the Shoreline fault zone.5.4.3.6 Slip rate Similar to assessing activity, the offshore location of the Shoreline fault zone makes it difficult to develop direct quantitative estimates of slip rate. The MBES bathymetric data were extensively probed to identify piercing points (i.e., potentially datable geomorphic features such as paleostrandlines or submerged channels on both sides of the fault zone that could be used to constrain cumulative slip and slip rate). No geomorphic features that could be reliably used as offset markers were observed, hence no conclusive piercing points were identified.
In the absence of more direct information, important constraints to slip rate are provided by four qualitative and indirect quantitative estimates of slip rate. These are summarized below: (1) Comparison to the Hosgri-San Simeon fault system. The Hosgri-San Simeon fault system has a slip rate in the range of 0.5 to 6 mm/yr, with a preferred rate of 1 to 3 mm/yr (PG&E, 1988; 1990; Hanson and Lettis, 1994; Hall et al., 1994; Hanson et al., 2004). Onshore, the San Simeon fault is well expressed geomorphically and clearly displaces late Pleistocene and Holocene deposits at numerous locations.
Offshore, the Hosgri fault zone locally produces scarps on the sea floor, and, along the reach of the fault directly west of the Irish Hills, abruptly truncates the westward extent of the offshore bedrock platform.
In addition, individual fault strands within the Hosgri fault zone produce linear escarpments in bedrock that appear to be pressure ridges on the sea floor. All of these features on the Hosgri fault zone occur in water depths shallower than 120 meters, and thus if present at the time of the last transgression, were subject to erosion. The Shoreline fault zone is not associated with similar geomorphic or geologic features identified on the Hosgri fault zone offshore or with the San Simeon fault zone onshore, with the-exception of the distinct lineament west of Olson Hill (Figure B-5-7) and the lineament and scarp west of the Intake Cove (Figure B-5-5) discussed above. Elsewhere along the Shoreline fault zone, geomorphic features of high slip-rate faults are lacking, even in locations where the fault zone extends into deeper water where the rapid rise in sea level since the last glacial maximum would not have destroyed significant fault features (Appendix I).Shoreline Fault Zone Report, Appendix B Geology Page B-35 ofl112 In addition, if the Shoreline fault zone had a slip rate comparable to the Hosgri-San Simeon fault system, it is likely that it would have maintained a seafloor expression southwest of Point San Luis, and evidence of higher slip-rate faults in the associated Southwest Boundary zone would be evident onshore in the vicinity of San Luis Obispo Bay or the Santa Maria Valley. Despite extensive onshore mapping in this area both during the LTSP and during this study, no faults with comparable geomorphic expression to the San Simeon fault have been identified.
Based on these observations, the slip rate on the Shoreline fault zone is qualitatively estimated to be an order of magnitude less that the slip rate on the Hosgri-San Simeon fault zone. This qualitative comparison yields an estimate of slip rate in the range of 0.05 to 0.6 mm/yr for the Shoreline fault zone.(2) Estimates of vertical separation.
Two approaches are used to constrain the amount of vertical separation on the Shoreline fault zone. Along the North segment (associated with the northern seismicity sub-lineament), possible displaced Tertiary strata from high-resolution seismic-reflection profiles are interpreted to constrain the cumulative amount of vertical separation on the segment to be about 5 to 10 meters, with a northeast-side down vertical separation.
The northeast-side down sense of vertical separation is opposite the expected northeast-side up vertical separation if the fault is partially accommodating uplift of the San Luis/Pismo block. In addition to the apparent limited vertical stratigraphic separation, the similarity in the seismic stratigraphy across the fault zone observed at these two locations probably indicates limited lateral displacement as well. These interpreted faults are similar to the faults imaged in the MBES bathymetric data that are associated with seafloor-exposed folds in the Monterey and Pismo Formations west of Point Buchon.The second approach to constrain vertical separation rates across mapped traces of the Shoreline fault zone is based on evaluation of the submerged wave-cut platforms that are mapped across the N40W and Central and South segments as described above in Section 5.4.3.5 and in Appendix I, Section 7.3. Estimates of vertical separation rate at the four sites are summarized from north to south below:* N4OWfault 
-The estimated vertical separation of the wave-cut platform associated with the -38 rn paleostrandline across the N40W fault is zero with an uncertainty of approximately 
+/- 2 meters (Section 5.4.3.5 and Appendix I, Section 7.3.1). Using the vertical separation and the estimated age of 49,000 to 60,000 years for the wave-cut platform yields a vertical separation rate of 0 +/- 0.04 mm/yr (i.e., with either a northeast-or southwest-side up sense of vertical separation).
* Central segment, sub-segment C-1 -The estimated vertical separation of the buried wave-cut platform associated with the -25 m paleostrandline across the C-1 sub-segment of the Shoreline fault zone is either 0 (from the preferred interpretation that the apparent scarp is due to differential erosion) or 1 +/- 2.5 meters with the center value having a northeast-side up vertical separation (Section 5.4.3.5 and Appendix I, Section 7.3.2).Using the vertical separation and the estimated minimum age of 75,000 years for the wave-cut platform yields a vertical separation rate of 0 or 0.01 +/- 0.03 mm/yr.* Central segment, sub-segment C-2 -The estimated vertical separation of the wave-cut platform associated with the -21 m paleostrandline across the C-2 sub-segment of the Shoreline fault zone is zero with an uncertainty of approximately 
+/- 1.5 mm/yr (Section 5.4.3.5 and Appendix I, Section 7.3.2). Using the vertical separation and the estimated Shoreline Fault Zone Report, Appendix B Geology Page B-3 6 of 112 minimum age of 75,000 years for the wave-cut platform yields a vertical separation rate of 0 +/- 0.02 mm/yr.* South segment -The estimated vertical separation of the wave-cut platform associated with the -31 m paleostrandline across the South segment of the Shoreline fault zone is zero with an uncertainty of approximately 
+ 1.5 mm/yr (Section 5.4.3.5 and Appendix I, Section 7.3.3). Using the vertical separation and the estimated minimum age of 75,000 years for the wave-cut platform yields a vertical separation rate of 0 +/- 0.02 mm/yr.The results summarized above suggest that the vertical separation rate on the Shoreline fault zone is indistinguishable from zero. In order to estimate a maximum horizontal slip rate from the wave-cut platform data, the maximum vertical separation rates are considered with a fault having an assumed 10:1 horizontal to vertical slip ratio. This assumption yields maximum horizontal slip rates on the order of 0.2 to 0.4 mm/yr.(3) Estimates of cumulative right-lateral strike-slip displacement.
Toward the northern end of the Central segment of the Shoreline fault zone, directly west of Discharge Cove, two west-northwest-trending, subparallel magnetic anomaly highs show an apparent right-lateral step of about 300 meters (Figure B-5-1). Although not a unique interpretation, the apparent right-lateral step occurs across a N15E striking basement fault whose north end aligns with the north-south to N25 0 W striking fault mapped in the headland at the northwest end of Discharge Cove. The mapped fault onshore and in the rocks at low tide juxtaposes two Obispo Formation units: resistant tuff against bedded sedimentary rock in a broad zone of shearing that is associated with hydrothermal alteration.
The N15&deg;E fault is truncated to the north by an east-west-striking fault that is clearly mapped in the intertidal zone and in the sea cliff (Plate B-1B; Figure B-5-1). This east-west fault does not displace an approximately 80,000 year-old wave-cut platform exposed in the sea cliff. Similarly, approximately north-south-striking faults mapped elsewhere in the direct vicinity of DCPP exhibit right-lateral separation, supporting the interpretation that the right-lateral separation in the magnetic anomaly highs reflects offset bedrock structure.
The interpreted N15&deg;E fault provides a possible piercing line or strain gauge from which to estimate cumulative right-lateral displacement where the Central segment of the Shoreline fault crosses the N15 0 E fault. Alternative interpretations of possible traces of the N15&deg;E fault through the MBES bathymetric data that satisfy the right-lateral separation in the twin magnetic anomaly highs, limits the possible offset to less than 100 meters (possibly 200 meters) right-lateral, and possibly zero (Figure B-5-1). Estimating an onset of deformatioriat between 1 and 2 million years ago (coinciding with the estimated onset of block uplift recorded by emergent marine terraces on the adjacent coast (Hanson et al., 1994) the horizontal slip rate of the fault would be no more than about 0.05 to 0.2 mm/yr, and could be zero.(4) San Luis Bay fault zone. An alternative structural interpretation of the Shoreline fault zone is that it is kinematically linked to the San Luis Bay fault zone such that the slip on the North and Central segments of the Shoreline fault zone continues onshore and follows the Rattlesnake fault of the San Luis Bay fault zone and forms part of a strike-slip restraining bend (Plates B-IC and ID; Figure B-5-8). In characterizations based on this linked structural model, the slip rate on the San Luis Bay fault zone can be used to provide information on the slip rate of the Shoreline fault zone. The San Luis Bay fault zone has a cumulative rate of vertical separation of 0.14 mm/yr as recorded in the emergent marine terraces at the coast, with about half of that vertical rate occurring on the Rattlesnake fault (PG&E, 1990; Hanson et al., 1994).In addition, detailed mapping along the coastline shows steeply (approximately 70 degrees)Shoreline Fault Zone Report, Appendix B Geology Page B-37 of 112 north-dipping beds of Cretaceous sandstone and siltstone across the Rattlesnake fault (Figure B-5-10). Tentative correlation of an approximately 35- to 40-meter-thick sequence of resistant sandstone beds on the modem wave-cut platform across the Rattlesnake fault yields an estimate of about 70 +/- 20 meters of apparent right-lateral separation across the fault, indicating that the Rattlesnake fault does not have significant cumulative deformation across it. Because the beds dip steeply to the north, the apparent right-lateral separation is consistent with pure north-side up dip-slip motion on a vertical fault of about 190 meters. Oblique motion of the Rattlesnake fault would yield a range of horizontal displacements up to approximately 70 meters (consistent with pure strike-slip displacement).
An estimated onset of deformation of 1 to 2 million years ago and a maximum horizontal displacement of 70 meters yields a limiting lateral slip rate of about 0.14 to 0.07 mm/yr. The absolute maximum lateral slip rate on the fault would be obtained by considering the limiting horizontal offset of 70 meters and a minimum age of 120,000 years, the age of the marine terrace that records the offset of the Rattlesnake fault. In this very unlikely consideration, the extreme maximum lateral slip rate would be about 0.6 mm/yr. Given the roughly equal distribution of vertical separation between the Rattlesnake fault and Olson deformation zone, the lateral slip rate is also assumed to be equally distributed, giving a cumulative absolute maximum lateral slip rate for the entire San Luis Bay fault zone of 1.2 mm/yr. As described earlier, given the absence of geomorphic expression onshore along the San Luis Bay fault zone similar to the San Simeon fault, a slip rate of over 1 mm/yr is not credible.Thus, this analysis concludes that a lateral slip rate of up to 1 mm/yr may branch from the San Luis Bay fault onto the Shoreline fault zone.Given the above four lines of reasoning, the slip rate on the Shoreline fault zone ranges from 0.05 to possibly 1 mm/yr, with a preferred value of about 0.2 to 0.3 mm/yr. The slip rate could also be zero.5.4.3.7 Relationship to other structures The Shoreline fault zone lies between the active Hosgri fault zone on the west and faults of the Southwest Boundary fault zone on the south and east: the Los Berros, Oceano, Wilmar Avenue, and San Luis Bay faults. Two alternatives are considered for the kinematic relationship of the Shoreline fault zone to adjoining structures.
One alternative, named herein the "independent fault" alternative, is that the Shoreline fault, zone is an independent strike-slip fault that may or may not branch from the Hosgri fault zone. In this alternative, the Shoreline fault zone does not accommodate uplift of the Irish Hills but rather is a strike-slip fault within the uplifting block and occurs in the hanging wall of the Hosgri, Los Osos, and San Luis Bay fault zones that are responsible for uplift of the range. In the second alternative, flamed herein the "linked fault" alternative, the Shoreline fault zone is kinematically linked to the San Luis Bay fault zone, and possibly to other faults of the Southwest Boundary fault zone to the south (i.e., the Los Berros, Wilmar Avenue, and Oceano faults). In this scenario, the Shoreline fault zone is part of a system of strike-slip and oblique-slip faults that border the southwestern margin of the uplifting San Luis/Pismo structural block, and slip rate on the San Luis Bay fault zone may be used to provide information on slip rate on the Shoreline fault zone, as discussed above.In the "independent fault" alternative, the western extent of the San Luis Bay fault zone would cross the Shoreline fault zone and extend to the Hosgri fault zone to accommodate uplift of the Irish Hills portion of the San Luis/Pismo block. In the "linked fault" alternative, the San Luis Bay fault zone proper likely ends or merges with the Shoreline fault zone and does not extend farther west to the Hosgri fault zone. In this case, the Shoreline fault zone is predicted to be an Shoreline Fault Zone Report, Appendix B Geology Page B-38 of 112 uplift rate boundary and accommodate a significant oblique component of slip. This alternative is not consistent with the evidence from wave-cut platforms that are crossed by the Shoreline fault zone and show minor, if any, vertical separation.
However, within the "linked fault" alternative there may be other kinematic models that do not require the Shoreline fault zone to be an uplift rate boundary.
For example, the Shoreline fault zone may act as a strike-slip fault as part of the Southwestern Boundary fault zone, and differential uplift between the Islay and Santa Rosa Reef shelves may be accommodated by other structures, including the steeply east-dipping Hosgri fault zone and the southwest-dipping Los Osos fault zone.5.4.4 San Luis Bay fault zone The San Luis Bay fault zone is part of the longer Southwestern Boundary fault zone that forms the southwestern boundary of the uplifting San Luis/Pismo structural block (PG&E, 1990; Lettis et al., 1994; 2004). The late Quaternary-active and approximately east-west-striking San Luis Bay fault zone contains one or more fault strands and accommodates north-side-up vertical displacement and an unknown amount of horizontal displacement.
At a minimum, the San Luis Bay fault zone is located between the Pacific coast near Rattlesnake Creek, across a low saddle separating San Luis, Hill from the rest of the Irish Hills, and eastward to the mouth of San Luis Obispo Creek (Avila Beach) where a strand of the fault zone is exposed faulting Franciscan rocks over alluvium (Figure B-4-1). Detailed mapping of the stream exposure and radiocarbon dating of faulted fluvial terrace deposits shows approximately 20 centimeters of apparent vertical separation since about 20,000 years ago (PG&E, 1990). Along the sea cliff directly west of San Luis Obispo Creek (exposures now covered), the fault juxtaposes Franciscan Complex rocks over the Squire Member of the Pismo Formation.
At these two locations, fault exposures suggest a moderate dip to the north, and, in one location, striations are consistent with dip-slip movement.
The continuation of the San Luis Bay fault zone across the saddle north of San Luis Hill without a significant deviation in trend suggests the average dip of the San Luis Bay fault zone is probably steep (70 degrees or higher) rather than moderate (PG&E, 1988; 1990).As the extent of the fault has not been directly observed, the eastern and western ends of the fault zone must be inferred based on structural and geomorphic observations.
East of San Luis Obispo Creek, the San Luis Bay fault zone probably continues to about Mallagh Landing (Figure B-4-1).Here, geologic mapping suggests a complex intersection between the northwest-striking San Miguelito fault zone and the northeast-striking Avila fault (PG&E, 1990). Interpretation of MBES bathymetric data and integration with mapping performed during the LTSP suggest that the San Miguelito fault probably continues to the southeast from Mallagh Landing and juxtaposes Obispo Formation on the southwest against a syncline of Monterey and Pismo Formation strata on the northeast (Plate B-1D). Thus the eastern limit of the San Luis Bay fault is considered to be at the intersection with the through-going San Miguelito fault and conjugate Avila fault near Mallagh Landing.The western end of-the San Luis Bay fault zone and its relationship with the Shoreline fault zone is also uncertain.
At the coast, the San Luis Bay fault zone consists of two separate structures, the Rattlesnake fault and the more northerly Olson Hill deformation zone (called the Olson fault in the LTSP reports) (Plate B-1C) (PG&E, 1988; 1990). These structures were identified based on the analysis of longitudinal profiles of emergent marine terrace shoreline angles that show down-to-the south offsets of the 80,000 and 120,000 year old marine terraces dating to sea-level highstands during the last interglacial interval (MIS 5a and 5e, respectively) (PG&E, 1990;Hanson et al., 1994). Borehole and survey data define a narrow warp or step in the buried Shoreline Fault Zone Report, Appendix B Geology Page B-39 of 112 120,000 year-old wave-cut platform directly west of Rattlesnake Creek (PG&E, 1990).Likewise, borehole and map data show down-to-the south deformation of the 80,000 and 120,000 year old shoreline angles across Olson Hill (Figure B-5-7). The current elevations of these terraces and estimates of paleosea level at the time of their formation provide estimates of uplift rate north of Olson Hill (0.2 mm/yr), between the Olson Hill deformation zone and Rattlesnake faults (0.14 mm/yr), and south of the Rattlesnake fault (0.06 mm/yr). The differential uplift rate across the San Luis Bay fault zone is about 0.14 mm/yr, with about 0.08 mm/yr uplift rate across the Rattlesnake fault and 0.06 mm/yr uplift rate across the Olson Hill deformation zone (PG&E, 1990; Hanson et al., 1994). In this report, we informally name the portion of the San Luis/Pismo block uplifting at 0.2 mm/yr north of the San Luis Bay fault zone the Irish Hills sub-block, and the portion uplifting at 0.06 mm/yr south of the San Luis Bay fault zone the Point San Luis sub-block.
5.4.4.1 Bedrock exposures of the San Luis Bay fault zone Although the geomorphic evidence for and quantification of differential uplift rates at the coast are clear, the exact location of the faults in bedrock at the coastline is not. A primary objective of the coastline geologic mapping was to identify and characterize the active Rattlesnake fault and bedrock faults near Olson Hill within the sea cliff and/or modem wave-cut platform exposed at low tide.Rattlesnake fault The bedrock geology at the coast across the Rattlesnake fault consists of steeply dipping and bedded Cretaceous sandstone (Figures B-5-8, B-5-10, and Plate B-IC). The strata in the direct vicinity of the active fault generally strike approximately east-southeast and bedding-up indicators within the siltstone and sandstone sequence consistently suggest the beds are overturned with steep dips to the north-northeast of about 70 degrees..
Brittle, penetrative fabric within siltstone interbeds record significant bedding-parallel shear within the unit, and detailed mapping shows several minor faults and sub-vertical-axis folds cutting and folding bedding.Based on the step or warp in the buried wave-cut platform, the exact location of the Rattlesnake fault is constrained to be within a southwest-facing cove that has a coarse sandy beach and a combination of bedrock and shallow slide/slump debris covering the sea cliff (Figure B-5-10).Structural bedrock mapping and observations of the emergent paleo-wave-cut platform suggest the Rattlesnake fault may intersect the sea cliff at one or both of two locations, labeled"Rattlesnake fault #1" and "Rattlesnake fault #2" on Figure B-5-10. The exact fault planes were not identified in the field as they are obscured by shallow slide debris derived from deposits capping the wave-cut platform.
In addition, slumping or sliding has obscured the contact K between bedrock and overlying deposits (the wave-cut platform) so that it could not be directly evaluated whether the wave-cut platform was discretely offset across one or.both of the alternative fault strand locations.
At the base of the sea cliff at the location of the "Rattlesnake fault #1" trace is a narrow zone of saturated clayey gouge and seeps, although it is unclear whether the sheared rock represent older bedding-parallel shears that are common in the strata or the active fault strand. South of the "Rattlesnake fault #2" trace is a clear wave-cut platform with overlying marine sands, but north of the trace the equivalent wave-cut platform with overlying marine deposits was not exposed. A higher wave-cut platform with no capping marine deposits is visible as discontinuous fragments, but this higher surface may represent paleo-sea-stacks and not the offset equivalent wave-cut platform surface. Both traces project seaward Shoreline Fault Zone Report, Appendix B Geology -Page B-40 of 112 towards the lineament mapped in the MBES bathymetric data and suggest a branching relationship between the Rattlesnake fault and the Shoreline fault (Figure B-5-8).The similarity of Cretaceous strata across the Rattlesnake fault suggests that cumulative offset of the Rattlesnake fault is limited, and the Rattlesnake fault here is not reactivating a pre-existing fault. One possible measure of the cumulative offset comes from a sequence of similar thick.sandstone beds with thin sandy and silty interbeds that are observed on either side of the fault (Figure B-5-10). These sequences are about 35 to 40 meters thick, overturned with an approximately70 degree dip to the north, bounded on the landward side by a sequence of thin sandstone and siltstone beds that record significant bedding-parallel shear, and bounded on the seaward side by a row of eroded sea stacks that may represent a correlative resistant bed. These sedimentary packages, if correlatives, show right-lateral separations on the order of 50 to 70 meters (Figure B-5-10). Because the beds dip steeply to the north, the apparent right-lateral separation is consistent with end-members of pure strikes-slip or pure north-side up dip-slip motion. If the apparent right-lateral separation is caused by dip-slip motion, the total amount is estimated based on a vertical fault to be about (70 meters
* tan(70&deg;) = 190 meters). Thus, cumulative displacement between about 70 and. 190 meters in about 0.5 to 2 million years yields slip rates that are on the same order as the 0.08 mm/yr vertical rate on the Rattlesnake fault calculated based on the offset 120,000 year old marine terrace.Olson Hill deformation zone Exposed in the bedrock geology near Olson Hill are several faults that juxtapose Franciscan complex greenstone, chert, and m~lange and blocks of Cretaceous sandstone (Figure B-2-2, B-5-7, and Plate B-i C). The narrow wave-cut platform and sea cliff north and south of Olson Hill provide excellent and almost continuous exposure of bedrock under low tide conditions, with very limited reaches of the coastline that cannot be accessed safely. The bedrock faults near Olson Hill include the North Olson fault north of Olson Hill, the South Olson fault directly south of Olson Hill, an unnamed fault zone farther south exposed near the mouth of Deer Creek, and the Double Rock fault exposed southeast of Double Rock. These bedrock'faults are all clearly exposed in the sea cliff, dip subvertically, juxtapose Cretaceous sandstone and Franciscan Complex rocks, and contain several meters of penetrative, fissile fault rock indicating that these are pre-existing faults with significant cumulative displacement that may date to coast-parallel subduction.
The North Olson, South Olson, and Double Rock faults all strike east-northeast, and their offshore projections do not correlate with well-defined lineaments observed in the MBES bathymetric data and thus do not clearly connect with the Shoreline fault zone (Figures B-2-2 and B-5-7). Furthermore, these faults do not appear to offset the overlying wave-cut platform.The fourth fault zone located near the mouth of Deer Creek between Olson Hill and Double Rock has ambiguous structural relationships such that it is unclear whether the fault is itself tightly folded or whether it cross-cuts a fold. This unnamed fault is observed beneath the coastal terraces to strike in a coast-parallel northwest-southeast trend and sub-parallel to the Shoreline fault zone. The relationship between this bedrock fault and the overlying wave-cut platform is ambiguous and partially obscured by vegetation that exists within the mouth of Deer Creek.Nevertheless, no clear and direct observations were made in the field to correlate the offset Pleistocene marine terraces across the Olson Hill area with discrete bedrock fault offsets. Based on the data points defining the shoreline angle of the 120,000 year old terrace (Figure B-5-7)(PG&E, 1990; Hanson et al., 1994), it is probable that the deformation across the Olson Hill area Shoreline Fault Zone Report, Appendix B Geology Page B-41 of 112 occurs as a southwest-facing monoclinal fold, herein named the Olson Hill deformation zone, between north of Olson Hill and Double Rock and not as a discrete fault offset.5.4.4.2 Westward offshore extent of the San Luis Bay fault zone*The offshore extent of the San Luis Bay fault zone is uncertain.
As stated above, there is a reasonable connection between the likely intersection of the Rattlesnake fault at the coast and a lineament mapped in the MBES bathymetric data that suggests a branching relationship between theRattlesnake and Shoreline faults (Figure B-5-8). Therefore, one reasonable western limit of the San Luis Bay fault zone is at the Shoreline fault zone. This endpoint and the eastern endpoint at Mallagh Landing yields an 8 km-long fault (Figure B-4-1). In this scenario, the Shoreline fault zone may be considered a part of the Southwestern Boundary fault zone that accommodates relative uplift between the Irish Hills and Point San Luis sub-blocks.
However, as described above in Section 5.4.3 and in Appendix I, there is evidence suggesting a zero to low vertical displacement rate across the Shoreline fault zone.Alternatively, multiple lines of evidence suggest that a broad structural boundary separating two sub-blocks with different uplift rates exists in the offshore west of the Shoreline fault zone along the westward continuation of the onshore San Luis Bay fault zone. The lines of evidence suggesting the westward continuation of the San Luis Bay fault zone include: (1) a west-northwest-trending magnetic intensity anomaly that continues along trend with the San Luis Bay fault zone west of the Shoreline fault (Appendix D); (2) the broad boundary in the offshore geologic map between pre-Tertiary bedrock to the north and Tertiary deposits to the South (particularly the northern limit of Obispo Formation southwest of the Shoreline fault), suggesting north-side-up structural relief (Figure B-4-1 and Plates B-1B and B-IC); (3) permissible correlation of submerged marine terraces south and north of the magnetic anomaly consistent with an uplift rate boundary separating the Santa Rosa Reef and Islay shelves there (Appendix I, Section xx), and (4) apparent deformation of the approximately 80,000 year old (MIS 5a) wave-cut platform in the nearshore across the Rattlesnake fault and Olson Hill deformation zone (Appendix I, Section. 7.3 and Figure 1-7-1). The offset MIS 5a wave-cut platform suggests that deformation of the terraces onshore documented in the LTSP (PG&E, 1990) continues offshore and across the Shoreline fault zone.The geologic map indicates a west-northwest trending structural grain between the coastline and the Hosgri fault zone along this possible westward continuation of the San Luis Bay fault zone, but the MBES bathymetric data do not show a through-going fault zone at the seafloor along this trend. This finding is consistent with the westward continuation of the San Luis Bay fault zone as a south-facing monoclinal flexure separating the Irish Hills and Point San Luis sub-blocks west of the Shoreline fault zone and extending to the Hosgri fault zone. This alternative relationship is generally consistent with the findings near Olson Hill that the 120,000-year-old (MIS 5e) terrace may be deformed in a monoclinal warp instead of as a discrete offset across a mapped fault, and would imply that the San Luis Bay fault zone may be partially blind at the coast and offshore, with only some strands (such as the Rattlesnake fault) intersecting the surface.Shoreline Fault Zone Report, Appendix B Geology Page B-42 of 112 
: 6. CONCLUSIONS The following conclusions are based on the data and analyses presented above.Data bases 1. The low-tide LiDAR and concurrent air photos of the coastal strip allowed detailed geologic mapping of the stratigraphy and structure of the nearly continuous exposures to be correlated with the detailed MBES bathymetry offshore and topography onshore. This allowed interpretation and correlation of geologic units and structures onshore and offshore referenced to a GIS database.2. MBES bathymetric images provided, in places, continuous coverage of bedrock and permitted accurate depiction of geologic structures and separation of rock types by textures.3. The offshore high-resolution seismic-reflection profiles at 800- and 400-meter spacing provided limited interpretations of structures in the areas covered by marine deposits and mobile sand sheets.4. The detailed magnetic-field maps from the marine survey and particularly the helicopter surveys helped delineate bedrock structures and differentiate rock types in the Obispo Formation and Franciscan Complex.5. Reinterpretation of the LTSP diver samples and drop cores combined with the new diver samples clarified some questionable stratigraphic and structural relationships offshore.Integration to make onshore-offshore geologic map 1. Combining all the information allowed for the interpretation of the geology and the creation of a nearly seamless onshore-offshore geologic map. This detailed geologic map illustrates what can be accomplished using the various types of data acquired for this study.Shoreline fault zone 1. The Central and South segments of the Shoreline fault zone are clearly expressed as a strong lineament on the MBES bathymetric image and have distinct magnetic-field signatures.
: a. Vertical displacement is less than 1 to 2 meters in the past 75,000 years providing a vertical separation rate of zero to < 0.02 mm/yr.b. Horizontal displacement is difficult to measure as no definitive geologic or geomorphic piercing points were identified.
However, an inferred, north-south striking fault mapped based on apparent offsets of magnetic anomalies across the Central segment of the Shoreline fault zone suggests limited right-lateral offset of the Shoreline fault zone (range is 0 to less than 200 meters and probably less than 100 meters). If this deformation has occurred in the past 1 .to 2 million years, this possible piercing line indicates an estimated slip rate of zero to less than 0.05 to 0.2 mm/yr.2. Some important characteristics remain uncertain, including:
: a. The relationship between the Shoreline fault zone and the Southwestern Boundary zone, in particular the San Luis Bay fault zone.Shoreline Fault Zone Report, Appendix B Geology Page B-43 of 112 
: b. The geologic character of the North segment of the Shoreline fault zone. It may or may not be expressed as the small faults in Tertiary strata that overlie the seismicity trend; an alternative interpretation that it coincides with the N40W fault is permissible but not preferred.
: c. The connection between the N40W fault and the Central segment of the Shoreline fault;and, d. The late Quaternary horizontal slip rate on the Shoreline fault zone. Current best estimates of horizontal slip rate are based on comparisons to other faults with measured slip rates and constraints on offset of inferred structures based on magnetic anomaly trends.Shoreline Fault Zone Report, Appendix B Geology Page B-44 of 112 
: 7. REFERENCES Atwater, T.M., 1970, Implications of plate tectonics for the Cenozoic tectonic evolution of western North America: Geological Society of America Bulletin, v. 81, p. 3513-3536.
Atwater, T.M., 1998, Plate tectonic history of southern California with emphasis on the western Transverse Ranges and northern Channel Islands, in Weigand, P.W., ed., Contributions to the Geology of the Northern Channel Islands, Southern California:
American Association of Petroleum Geologists, Pacific Section, MP 45, p. 1-8.Atwater, T.M., and Stock J., 1998, Pacific-North America plate tectonics of the Neogene southwestern United States-an update: International Geological Review, v. 40, p. 375-402.Compton, R.R., 1985, Geology in the Field: John Wiley and Sons, New York.Ducea, M., House, M.A., Kidder, S., 2003, Late Cenozoic denudation and uplift rates in the Santa Lucia Mountains, California:
Geology, v. 31, p. 139-142.Hall, C.A., 1973a, Geologic map of the Morro Bay South and Port San Luis quadrangles, San Luis Obispo County, California:
US Geological Survey Miscellaneous Field Studies Map MF-51 1, scale 1:24,000.Hall, C.A., 1973b, Geologic map of theArroyo Grande quadrangle, San Luis Obispo County, California:
California Division of Mines and Geology Map Sheet 24, scale 1:48,000.Hall, C.A., and Surdam, R.C., 1967, Geology of the San Luis Obispo-Nipomo Area, San Luis Obispo County, CA, Geological Society of America Cordilleran Section Guidebook.
Hall, C.A., Ernst, W.G., Prior, S.W., and Wiese, J.W., 1979, Geologic map of the San Luis Obispo-San Simeon region, California:
US Geological Survey Miscellaneous Investigations Series Map 1-1097, scale 1:48,000.Hanson, K.L., Wesling, J.R., Lettis, W.R., Kelson, K.I., and Mezger, L., 1994, Correlation, ages, and uplift rates of Quaternary marine terraces:
South-central coastal California:
Geological Society of America Special Paper 292.Keller, M.A., 1992, Field guide to the upper' Miocene siliceous coastal sequence of Montana de Oro State Park, California, in Schwalbach, J.R., and Bohacs, K.M., eds., Sequence Stratigraphy in Fine-grained Rocks: Examples from the Monterey Formation:
Pacific Section, S6ciety of Economic Paleontologists and Mineralogists, Book 70, p. 67-80.Keller, M.A., and Barron, J.A., 1993, Re-evaluation of the Miguelito Member of the Pismo Formation of Montafia de Oro State Park, California, including new diatom age data [abs.]: American Association of Petroleum Geologists Bulletin, v. 77, p. 703-704.Lettis, W.R., and Hanson, K.L., 1992, Crustal strain partitioning; implications for seismic hazard assessment in western California:
Geology, v. 19, p. 559-562.Lettis, W.R., and Hall, N.T., 1994, Los Osos fault zone, San Luis Obispo County, California, in Alterman, I.B., McMullen, R.B., Cluff, L.S., and Slemmons, D.B., eds., Seismotectonics of the central California Coast Ranges: Geological Society of America Special Paper 292, p. 73-102.Lettis, W.R., Kelson, K.I., Wesling, J.R., Angell, M., Hanson, K.L., and Hall, N.T., 1994, Quaternary deformation of the San Luis Range, San Luis Obispo County, California, in Alterman, I.B., McMullen,'R.B., Cluff, L.S., and Slemmons, D.B., eds., Seismotectonics of the central California Coast Ranges: Geological Society of America Special Paper 292, p. 111-132.Lettis, W.R., Hanson, K.L., Unruh, J.R., McLaren, M., and Savage, W.U., 2004, Quaternary tectonic setting of south-central coastal California in Keller, M.A., ed., Evolution of Sedimentary Basins/Offshore Oil and Gas Investigations-Santa Maria Province:
U.S. Geological Survey Bulletin 1995-AA, p. 1-21.McCulloch, D.S., 1987, Regional geology and hydrocarbon potential of offshore central California:
in Scholl, D.W., Grantz, A., and Vedder, J., eds., Geology and Resource Potential of the Continental Margin of Western North America and Adjacent Ocean Basins, Beaufort Sea to Baja Calforinia; American Association of Petroleum Geologists Circum. Pacific Earth Science, v. 6, p. 353-401.Niemi,.F., Hall, N.T., and Shiller, G.I., 1987, Seafloor scarps along the central reach of the Hosgri fault southern Coast Ranges, California (abs.): Geological Society of America, v. 19, p. 789.Pacific Gas and Electric Company (PG&E), 1975, Final safety analysis report for Diablo Canyon Nuclear Power Plant, Appendix 2.5E: U.S. Nuclear Regulatory Commission Docket Nos. 50-275 and 50-323.Shoreline Fault Zone Report, Appendix B Geology Page B-45 of 112 Pacific Gas and Electric Company (PG&E), 1988, Final report of the Diablo Canyon Nuclear Long-Term Seismic Program for the Diablo Canyon Power Plant: U.S. Nuclear Regulatory Commission Docket Nos. 50-275 and 50-323.Pacific Gas and Electric Company (PG&E), 1989, Response to Question 43i:Diablo Canyon Long-Term Seismic Program: U.S. Nuclear Regulatory Commission Docket Nos. 50-275 and 50-323.Pacific Gas and Electric Company (PG&E), 1990, Response to Question GSG 16: Diablo Canyon Long-Term Seismic Program: U.S. Nuclear Regulatory Commission Docket Nos. 50-275 and 50-323.Pacific Gas and Electric Company (PG&E), 1991, Addendum to the 1988 Final Report of the Diablo Canyon Long Term Seismic Program.Pacific Gas and Electric Company (PG&E), 2002, Diablo Canyon Independent Spent Fuel Storage Installation Final Safety Analysis Report.Pacific Gas and Electric Company (PG&E), 2010, Progress Report on the analysis of the Shoreline fault zone, central coastal California:
Report to the U.S. Nuclear Regulatory Commission, PG&E Letter DCL-10-003, Page, B.M., Thompson, G.A., and Coleman, R.G., 1998, Late Cenozoic tectonics of the central and southern Coast Ranges of California:
Geological Society of America Bulletin, v. 110, p. 846-876.Schwalbach, J.R., and Bohacs, K.M., 1995, Stratigraphic sections and Gamma-ray spectrometry from five outcrops of the Monterey Formation in southwestern California:
Naples Beach, Point Pedernales, Lion's Head, Shell Beach, and Point Buchon: in Keller, M.A., ed., Evolution of Sedimentary Basins/Onshore Oil and Gas Investigations-Santa Maria province:
U.S. Geological Survey Bulletin 1995, Chapter Q.Stanley, K.O. and Surdham, R.C., 1984, The role of wrench faulting and relative changes of sea level on deposition of upper Miocene-Pliocene Pismo Formation, Pismo Syncline, California, in Surdam, R.C., ed., Stratigraphic, Tectonic, Thermal, and Diagenetic Histories of the Monterey Formation, Pismo and Huasna Basin, California:
Society of Economic Paleontologists and Mineralogists Guidebook No. 2, p. 21-37.Turner, D.L., 1970, Potassium-argon dating of Pacific coast Miocene foraminiferal stages, in Bandy, O.L., ed., Radiometric dating and paleontologic zonation:
Geological Society of America Special Paper 124, p. 91-129.Wahl, A.D., 1995, Cenozoic deformation of the Franciscan Complex, eastern Santa Maria basin, California:
in Keller, M.A., ed., Evolution of Sedimentary Basins/Onshore Oil and Gas Investigations-Santa Maria province: U.S. Geological Survey Bulletin 1995, Chapter Q.Wiegers, M.O., 2009, Geologic map of the Morro Bay South 7.5' Quadrangle, California Geological Survey, scale 1:24,000.Shoreline Fault Zone Report, Appendix B Geology Page B-46 of 112 Table B-1. Drop Core Samples from LTSP Table B-1. Drop Core Samples from LTSP.ample DeLTSP Sample LTSP Unit .2010Re-Date {oesrpto trtt 'Additional Comi'nents le- DescDLption 
.Interpretation -interpreta ion SE of ANTI-i- 17 oi Cretaceous Not located in area mapped for this 2DC 1974 Point "Greywacke" Sandstone (Ks) nla study 2DC Estero SW of Consistent with Miguelito Member AQ-24 1974 Morro "Argillite" Not determined Tmprn of the Pismo Formation, mapped Bay along coastline W of Pt. Probably Trm or Consistent with Monterey AQ-34 1974 San Argillaceous Monterey Trnor Formation or fine-grained subunit Luis Formation of the Obispo Formation AQ-101 1974 Estero Ultramafic rock Mesozoic nia Not located in area mapped for this Bay study W of Probably Not located in area mapped for this AQ-103 1974 Morro Silty argillite Monterey n/a study Bay Formation Wof Not located in area mapped for this AQ-104 1974 Morro Silty argillite Not determined n/a Bay study W of Not located in area mapped for this AQ-108 1974 Morro Argillite Not determined nlastudy Bay W of Consistent with Miguelito Member AQ-1 10' 1974 Morro Argillite Not determined Tmpm of the Pismo Formation, mapped Bay along coastline W of Consistent with Miguelito Member AQ-1 11 1974 Morro Silty argillite Not determined Tmpm of the Pismo Formation, mapped Bay along coastline SW of Probably Consistent with Miguelito Member AQ-1 13 1974 Morro Argillite Monterey Tmpm of the Pismo Formation, mapped Bay Formation along coastline SW of Consistent with Miguelito Member AQ-1 15 1974 Morro Argillite Not determined Tmpm of the Pismo Formation, mapped Bay along coastline San Bedded habit in bathymetric data is AQ-1 18 1974 Luis Greywacke Not determined Ks consistent with Cretaceous Bay Sandstone (Ks)sw of NCAL- S fNot located in 'area mapped for this 75-1G 1975 Pt. San Siltstone Not determined n/a study Luis Shoreline Fault Zone Report, Appendix B Geology Page B-47 of 112 Table B-1. Drop Core Samples from L TSP T ...Sample Date L LTSP Sample LTSP Unit 2010 Re-ID D'.. Description Interpretation interpretation Additional Comments NCALi SW of Bedded habit in bathymetric data is 75-1I 1975 Pt. San Sandstone Not determined Ks consistent with Cretaceous Luis Sandstone (Ks)SW of Bedded habit in bathymetric data is 75-1Jii 1975 Pt. San Sandstone Not determined Ks consistent with Cretaceous Luis Sandstone (Ks)NCAL- SW of Bedded habit in bathymetric data is 75-1 K 1975 Pt. San Sandstone Not determined Xs consistent with Cretaceous Luis Sandstone (Ks)NCAL- SW of Bedded habit in bathymetric data is 75-iL 1975 Pt. San Sandstone Not determined Ks consistent with Cretaceous Luis Sandstone (Ks)SW of Bedded habit in bathymetric data is N5- 1975 Pt. San Sandstone Not determined Ks consistent with Cretaceous Luis Sandstone (Ks)NCAL- SW of Bedded habit in bathymetric data is 75-1 Q 1975 Pt. San Sandstone Not determined Ks consistent with Cretaceous Luis Sandstone (Ks)NCAL-W of Stratigraphic position and lithology 15-2A ofPt Sandstone oi t de tomie To is consistent with Obispo Formation 75-1AQ 97 Sans stonetoMocene Luis W of Pt.NCAL- Sandstone/silt Miarly tocmiddle Stratigraphic position and lithology 75-2B 1975eSa is consistent with Obispo Formation Luis NCAL- W975 San Sandstone/sha M iddle Stratigraphic position and lithology 75-2C ofPt San stone / Eomide Tmo is consistent with Obispo Formation Luis stnMoce NCAL- Wof Pt. Early to middle Stratigraphic position and lithology 75-2D 1975 San Siltstone.
E Miocene Tmo is consistent with Obispo Formation Luis n/hl icn NCAL- W of Pt. Sandstone/lmu Middle (?) Stratigraphic position and lithology 75-2H LS Miocene S is consistent with Obispo Formation NCAL- S Sdstoner Mie Tmo Stratigraphic position and lithology 75-2W 1975 dshale oPo.ene is consistent with Obispo Formation W olf Pt.NCAL- 1975 San Mud over Not determined Tmo Stratigraphic position and lithology 75-2M Luis shale is consistent with Obispo Formation NA-W of Pt. Siltstone or Stratigraphic position and lithology 7CA-M 1975 San Not determined TmoiscnsttwthbipFomin 75-2M ~~Luis shaleiscnitnwihOsoFrmin Shoreline Fault Zone Report, Appendix B Geology Page B-48 of 112 Table B-1. Drop Core Samples from LTSP Sk~le TSP Safple "LtSP- Unit , Date~e Location TPaipe LTPUi 00I Additional Comm6-ntsae L Descrilption, interpretation interpretation NCAL- W of Pt. Stratigraphic position and lithology 75-20 1975 San shale Not determined Tmm is consistent with Monterey Luis Formation W of Pt. Stratigraphic position and lithology NCAL- Clay/siltstone/li Monterey type TmiscnsttwihMtey 75-2Q 1975 San Tmm is consistent with Monterey Luis mestone lithology Formation NCAL- 1975 W of Pt. Stratigraphic position and lithology 75-3A San Siltstone/tuff Miocene (7) Tmo is consistent with Obispo Formation Luis NCAL- W of Pt. Stratigraphic position and lithology 75-3E 1975 San Shale Not determined Tram is consistent with Monterey Luis Formation NCAL- W of Pt. Stratigraphic position and lithology 75-3 1975 San Siliceous shale Not determined Trmm is consistent with Monterey Luis Formation NCAL- W of Pt. Stratigraphic position and lithology 75-3J 1975 San Siltstone Not determined To is consistent with Obispo Formation Luis W of Pt. Siltstone or Stratigraphic position and lithology N-3K 1975 San shale Not determined Tmm is consistent with Monterey Luis Formation W of Pt. Miocene type Stratigraphic position and lithology 75-3L 1975 San Siltstone/chert lithologyTm is consistent with Monterey Luis Formation NCAL- W of Pt. Miocene type Stratigraphic position and lithology 1975 San Siltstone io y Trm is consistent with Monterey 75-3N Luis Formation NCAL- 1975 sanW of Pt. Mudstone/siltst Middle or late Stratigraphic position and lithology 75-30 of t*id one/chert Miocene Tmo is consistent with Obispo Formation Luis onchr Micn NCAL W of Pt. Mud over Stratigraphic position and lithology 754 1975 San mudstone Not determined Trm is consistent with Monterey.Luis Formation W of Pt. Mud/sandston Stratigraphic position and lithology 75NCAL- 1975 San e Not determined Tram is consistent with Monterey Luis Formation NCAL- W of Pt. Stratigraphic position and lithology 1975 San Siltstone Not determined Tram is consistent with Monterey Luis Formation Shoreline Fault Zone Report, Appendix B Geology Page B-49 of 112 Table B-1. Drop Core Samples from LTSP Sample D LTSP Sample&#xfd; LTSP Unit 2010 Re- dDate Location.
ecit~ nt~rtio Additio'nal 
....Comments ,-.Decription' Interpfetaio ieipreatn W of Consistent with Miguelito Member NCAL- 195 Mro Mudstone/siltst 75-8C 1975 Morr one/shale Not determined Tmpm of the Pismo Formation, mapped Bay along coastline NCAL- W of Consistent withMiguelito Member 75-8G 1975 Morro Clay/silt Miocene (?) Tmpm of the Pismo Formation, mapped Bay along coastline NCAL- SW of Consistent with Miguelito Member 75-8H 1975 Morro Mudstone Not determined Tmpm of the Pismo Formation, mapped Bay along coastline SW of Miocene type Consistent with Miguelito Member 75-81 1975 Morro Shale lithology Tmpm of the Pismo Formation, mapped Bay along coastline SW of Consistent with Miguelito Member-1975 Morro ove Not determined Tmpm of the Pismo Formation, mapped 75-80 195 Mro shale Bay along coastline SW of Consistent with Miguelito Member NCAL- Mudstone/cher Middle ( Tmpm of the Pismo Formation, mapped 1975 Morro Miocene .along coastline SW of Consistent with Miguelito Member 75- 1975 Morro Mudstone Not determined Tmpm of the Pismo Formation, mapped 75-8S Bay along coastline NCAL- SW of Consistent with Miguelito Member 75-8T 1975 Morro Mudstone Not determined Tmpm of the Pismo Formation, mapped Bay along coastline NCAL- W of Consistent with Miguelito Member 75-98 1975 Morro Mudstone Not determined Tmpm of the Pismo Formation, mapped Bay .. along coastline W of Consistent with Miguelito Member 7CALC 1975 Morro Clay ove Not determined Tmpm of the Pismo Formation, mapped 75-9C mudstone Bay along coastline NCAL- W of Consistent with Miguelito Member 75-91 1975 Morro Clay over Middle to late Tmpm of the Pismo Formation, mapped Bay91shale/siltstone Miocene alnosln Bay along coastline NCAL- W of Sand over Consistent with Miguelito Member 75-9K .1975 Morro mudstone Not determined Tmpm of the Pismo Formation, mapped Bay along coastline NCAL- W of Sand over Consistent with Miguelito Member 1975 Morro Not determined Tmpm of the Pismo Formation, mapped 75-9N mudstone Bay .along coastline Shoreline Fault Zone Report, Appendix B Geology Page B-50 of 112 Table B-1. Drop Core Samples from LTSP Sampl ate LTSP Sample LTSP Unit 2010 Re- Additiohal.
Comments D D D~sripti6n lht6rpretation interrertation W of Consistent with Miguelito Member NA- 1975 Morro Siltstone Not determined Tmpm of the Pismo Formation, mapped Bay along coastline NCAL-W of Shale or Not located in area mapped for this 75-lOB 1975 Morro siltstone Not determined n/a study Bay NCAL- W of Clay over Quaternary Not located in area mapped for this 75-10E 1975 Morro siltstone coccoliths n/a study Bay NCAL- S of Pt. Quaternary Not located in area mapped for this 75-12F 1975 Estero Sand over clay coccoliths n/a study NCAL- 1975 W of Pt. Siltstone Late Miocene or n/a Not located in area mapped for this 75-17C Estero early Pliocene study NCAL- NW of Sand over Not located in area mapped for this 75-18A 1975 Pt. saeNot determined n/a study Estero shale NCAL- 1975 .of Sand over Not determined n/a Not located in area mapped for this 75-18E Estero sandstone study NCAL- NW of Sandstone Not located in area mapped for this 75-18F 1975 Pt. sandtsde Not determined n/ay Estero and shale NCAL- NW of Shale or Not located in area mapped for this 75-18G 1975 Pt. sandstone Not determined nla study Estero NCAL- W of Late M' Not located in area mapped for this 75-23A 1975 Cambria early Miocene study S of NCAL- 1975 San Siltstone Middle Miocene, nla Not located in area mapped for this 75-25A Simeon Relizian (?) study Pt.S of NCAL- 1975 San Siltstone Middle Miocene,.
n/a Not located in area mapped for this 75-25E Simeon Relizian (?) study Pt.S of NCAL- San Siltstone in Middle Miocene, Not located in area mapped for this 75-25F 1975 Simeon claymatrix Luisian n/a study I _Pt.Shoreline Fault Zone Report, Appendix B Geology Page B-51 of 112 Table B-2. Diver Samples from LTSP Table B-2. Diver Samples from L TSP sample Date Location ILTSP Sampie LTsP Unit .2010 Re- Additional Comments ID*. J -skriptfin interpretation interpretation 1 ., , ... 1' 1': DI/S1 10/30/1980 Santa Rosa "Black shale with Franciscan Ks Franciscan Complex rock is not Platform albite (?) veinlets" Complex mapped along coastline within 1800 (KJfm) meters of this location, this sample is probably from fine-grained interbeds within Cretaceous Sandstone D1/$2 10/30/1980 Santa Rosa "Massive, medium-gr.
Cretaceous Ks Franciscan Complex rock is not Platform greywacke; attitude Sandstone (Ks) mapped along coastline within 1800 on good planar or Franciscan meters of this location, this sample surface, but may not Complex (KJfg) is probably Cretaceous Sandstone be bedding" D2/$3 10/30/1980 Santa Rosa "Massive medium-gr.
Cretaceous Ks Franciscan Complex rock is not Platform greywacke, abundant Sandstone (Ks) mapped along coastline within 1800 biotite, resembles or Franciscan meters of this location, this sample Dive 1, Sta. 2" Complex (KJfg) is probably Cretaceous Sandstone D2/$4 10/30/1980 Santa Rosa "Same as Dive 2, Cretaceous Ks Franciscan Complex rock is not Platform Sta. 3" Sandstone (Ks) mapped along coastline within 1800 or Franciscan meters of this location, this sample Complex (KJfg) is probably Cretaceous Sandstone D3/$5 10/30/1980 Santa Rosa "Slickensided black Franciscan KJfm Consistent with Franciscan Platform shale similar to Dive Complex Complex rock mapped along the 1, Sta. 1" (KJfm) coastline D3/$6 10/30/1980 Santa Rosa "Red and green Franciscan KJfm Consistent with Franciscan Platform chert" Complex Complex rock mapped along the (KJfm) coastline D3/$7 10/30/1980 Santa Rosa "Medium-gr.
Cretaceous KXJ Consistent with Franciscan Platform greywacke" Sandstone (Ks) Complex rock mapped along the or Franciscan coastline Complex (KJfg)D4/$8 10/30/1980 Santa Rosa "Greenstone" Franciscan KJf Consistent with Franciscan Platform Complex -Complex rock mapped along the (KJfm) coastline D4/$9 10/30/1980 Santa Rosa "Very fine-gr, Franciscan KJf Consistent with Franciscan Platform Microgreywacke" Complex Complex rock mapped along the (KJfm) coastline D4/S10 10/30/1980 Santa Rosa "Serpentinite" Franciscan KJf Consistent with Franciscan Platform Complex Complex rock mapped along the (KJfm) coastline D5/S1 10/30/1980 Islay "Vesicular, zeolitized Obispo Tmor Consistent with resistant subunit of Platform tuff; attitude may be Formation (To) Obispo Formation mapped at on loose block" Crowbar D5/$2 10/30/1980 Islay "Orange-brown Obispo Tmor Consistent with resistant subunit of Platform zeolitized tuff; Formation (To) Obispo Formation mapped at attitude probably on Crowbar car-sized block" D5/$3 10/30/1980 Islay "White zeolitized tuff" Obispo Tmor Consistent with resistant subunit of Platform Formation (To) Obispo Formation mapped at Crowbar D6/$4 10/30/1980 Islay "Basalt; attitude may Unnamed Tmod Consistent with diabase mapped Platform be on flow or dike volcanic rocks along the coastline surface, or on joint" (Tvr)D6/S5 10/30/1980 Islay "Coarse-gr, Diabase" Unnamed Tmod Consistent with diabase mapped Platform volcanic rocks along the coastline S(Tvr)Shoreline Fault Zone Report, Appendix B Geology Page B-52 ofl112 Table B-2. Diver Samples from L TSP Sample L ['SPtSar mple LTITSP Unit 2010 Re-Ia Date D escription Interpretation AdditionalComments D7/$6 10/30/1980 Islay "Chert breccia" Monterey Trmm Consistent with Monterey Formation Platform Formation mapped along the coastline (Tmm)D7/$7 10/30/1980 Islay "Fractured, siliceous Monterey Tmm Consistent with Monterey Formation Platform claystone/chert" Formation mapped along the coastline (Tmm)D8/S8 10/30/1980 Islay "Massive brown Miguelito Tmpm Consistent with Pismo Formation Platform mudstone" Member of the mapped along the coastline Pismo Formation (Tpm)D8/$9 10/30/1980 Islay "Laminated opaline Miguelito Tmpm Consistent with Pismo Formation Platform claystone" Member of the mapped along the coastline Pismo Formation (Tpm)D9/S10a 10/30/1980 Islay "No sample taken; -nla No sample, not reinterpreted Platform sand/rock contact may be Los Osos fault (?)" D9/S10b 10/30/1980 Islay "No sample taken; -n/a No sample, not reinterpreted Platform sand/rock contact may be Los Osos fault (?)" D1 0/Si 1 10/30/1980 Santa Rosa "Gray, medium-gr, Pismo, Squire, Ks or Tpp This sample is probably from fine-Platform sandstone well- or Edna(?) grained interbeds within Cretaceous sorted sandstone" Members of the Sandstone, but may be Tertiary-age Pismo (Pismo or Obispo Formations)
Formation (Tp)D1 1/S1 11/1/1989 Santa Rosa "Gray, fine-gr, well- Squire Member Ks or Tpp This sample is probably from fine-Platform sorted sandstone" of the Pismo grained interbeds within Cretaceous Formation (Tps) Sandstone, but may be Tertiary-age (Pismo or Obispo Formations)
D1 1/S2 11/1/1989 Santa Rosa "Brown with white Miguelito Ks or Tpp This sample is probably from fine-Platform mottles, dolomitic Member of the grained interbeds within Cretaceous siltstone" Pismo Sandstone, but may be Tertiary-age Formation(?) (Pismo or Obispo Formations)(Tpm)Dl 1/S3 11/1/1989 Santa Rosa "Brown, crudely Miguelito Ks or Tpp This sample isprobably from fine-Platform bedded siltstone" Member of the grained interbeds within Cretaceous Pismo Sandstone, but may be Tertiary-age Formation(?) (Pismo or Obispo Formations)
_______(Tpm)
D12/$4 11/1/1989 Santa Rosa "Fine-gr. , tuffaceous Obispo Tmor/Tmof Stratigraphic position above basal Platform white sandstone, Formation(?)
Tertiary contact (recognized in outcrop trend (To) bathymetric data) is consistent with measured on 2 large resistant or fine-grained subunits of blocks" Obispo Formation D13/$5 11/1/1989 Santa Rosa "Orange-brown, Obispo Tmor/Tmof Stratigraphic position above basal Platform vesicular tuff" Formation (To) Tertiary contact (recognized in bathymetric data) is consistent with resistant or fine-grained subunits of Obispo Formation D14/S6 11/1/1989 Santa Rosa "Greenstone with Franciscan KJfmv Sample may be slightly mis-located, Platform minor pyrite" Complex should be from Pecho Rock (KJfmv)Shoreline Fault Zone Report, Appendix B Geology Page B-53 of 112 Table B-2. Diver Samples from L TSP Sample 1sP Sample LT1'Unit 010 Date Location Same LTSPU0 R- Additiona Comments ID* ' ' * -_ Description Interpretation interpretation i Comments D1 5/S7 11/1/1989 Santa Rosa "Gray, very fine-gr, Squire Member Ks or To/Tpp This sample is probably from within Platform Sandstone" of the Pismo Cretaceous Sandstone, but may be Formation (Tps) Tertiary-age (Pismo or Obispo Formations)
D15/$8 11/1/1989 Santa Rosa "Brownish gray, Miguelito Ks or To/Tpp This sample is probably from fine-Platform dolomitic siltstone; Member of the grained interbeds within Cretaceous resembles Dive 11, Pismo Sandstone, but may be Tertiary-age Sta. 2" Formation(?) (Pismo or Obispo Formations)(Tpm)D15/$9 11/1/1989 Santa Rosa "Dark brown, bedded, Miguelito Ks or To/Tpp This sample is probably from fine-Platform siltstone calcareous" Member of the grained interbeds within Cretaceous Pismo Sandstone, but may be Tertiary-age Formation(?) (Pismo or Obispo Formations)(Tpm)D16/S10 11/1/1989 Santa Rosa "Dark grayish brown, Miguelito Ks or To/Tpp This sample is probably from fine-Platform dolomitic siltstone; Member of the grained interbeds within Cretaceous resembles Dive 15, Pismo Sandstone, but may be Tertiary-age Sta. 9" Formation(?) (Pismo or Obispo Formations)(Tpm)D17/S1 11/2/1989 mislocated "Highly sheared Franciscan n/a sample mislocated greywacke Complex (Kjf)greenstone" D18/S2 11/2/1989 mislocated "Dark green, Cretaceous n/a sample mislocated medium-gr, hard Sandstone (Ks)greywacke; surfaces or Franciscan measured may be Complex (KJfg)joints" D18/$3 11/2/1989 mislocated "Same as Dive 18, Cretaceous n/a sample mislocated Sta. 2",, Sandstone (Ks)or Franciscan Complex (KJfg)D1 9/S4 11/2/1989 mislocated "Tan, fine-gr, mod. Cretaceous n/a. sample mislocated sorted greywacke" Sandstone (Ks)D19/$5 11/2/1989 mislocated "Greenish brown, Cretaceous n/a sample mislocated greywacke fine-gr, Sandstone (Ks)Micaceous" D19/$6 11/2/1989 mislocated "Greenish gray, fine- Cretaceous n/a sample mislocated gr, greywacke Sandstone (Ks)Grayish tan, fine-gr, Greywacke" D20/$7 11/2/1989 mislocated "Grayish tan, fine-gr. Cretaceous n/a sample mislocated Greywacke" Sandstone (Ks)D20/$8 11/2/1989 mislocated "Olive brown, fine-gr. Cretaceous n/a sample mislocated Greywacke" Sandstone (Ks)D21/S1 11/3/1989 Islay "Very dark brown, Monterey Tmm Sample located outside of the area Platform bedded siliceous Formation discussed in this report mudstone; tar in (Tmm)fractures" D21/$2 11/3/1989 Islay 'Very dark brown, Monterey Tmm Sample located outside of the area Platform laminated mudstone Formation discussed in this report (same color as Dive (Tmm)21, Sta, 1)" D21/S3 11/3/1989 Islay 'Very dark brown, Monterey Tmm Consistent with Monterey Formation Platform laminated chert and Formation mapped along the coastline siliceous mudstone; (Tmm)Shoreline Fault Zone Report, Appendix B Geology Page B-54 of 112 Table B-2. Diver Samples from L TSP Sample Date Location LTSP Sample LTSP Unit 2010 Re- Additional Comments ID* DateDLocation Description Interpretation interpretation tarry" D22/$4 11/3/1989 Islay "Med, to dark brown, Monterey Tmm Consistent with Monterey Formation Platform siliceous mudstone Formation mapped along the coastline laminated" (Tmm)D22/$5 11/3/1989 Islay "Med. to dark brown, Monterey Tmm Consistent with Monterey Formation Platform siliceous mudstone Formation mapped along the coastline with contorted (Tmm)laminations" D23/$6 11/3/1989 San Luis "White vitric tuff" Obispo Tmo Consistent with Obispo Formation Bay Formation (To) mapped along the coastline D24/$7 11/3/1989 San Luis "Light gray vitric tuff Obispo or Tmor Stratigraphic position above basal Bay to E; brownish black, Rincon(?)
Tertiary contact is consistent with mottled, hard Formations interbedded tuff and siltstone as siltstone to" To/Tr observed onshore in subunit Tmor of the Obispo Formation D25/$8 11/3/1989 San Luis "Gray to orange, Obispo Tmor Consistent with Obispo Formation Bay zeolitized, vesicular Formation (To) mapped along the coastline tuff with chalcedony veins" D26/S1 11/8/1989 Santa Rosa "Fine-gr, fractured Franciscan Ks or KJf Mapped as Cretaceous Sandstone Platform greywacke" Complex(?)
based on low magnetic values in (KJfg) or aerial survey data, could be Cretaceous Franciscan Complex rock Sandstone (Ks)D26/$2 11/8/1989 Santa Rosa "Fine-gr, biotite-rich Franciscan Ks or KJf Mapped as Cretaceous Sandstone Platform greywacke" Complex(?)
based on low magnetic values in (KJfg) or aerial survey data, could be Cretaceous Franciscan Complex rock Sandstone (Ks)D26/S3 11/8/1989 Santa Rosa "Fine-gr, slickensided Franciscan Ks or KJf Mapped as Cretaceous Sandstone Platform metagraywacke" Complex (KJfg) based on low magnetic values in aerial survey data, could be Franciscan Complex rock D27/$4 11/8/1989 Santa Rosa "Med-gr, micaceous Franciscan KJf or Ks Mapped as Franciscan greywacke Platform greywacke with Complex(?)
based on high magnetic values in slickensided shaly (KJfg) or aerial survey data, could be interbeds" Cretaceous Cretaceous Sandstone Sandstone (Ks)D27/$5 11/8/1989 Santa Rosa "Fine-gr, fractured Franciscan KJf or Ks Mapped as Franciscan greywacke Platform greywacke" Complex(?)
based on high magnetic values in (KJfg) or aerial survey data, could be Cretaceous Cretaceous Sandstone Sandstone (Ks)D27/$6 11/8/1989 Santa Rosa "Slickensided Franciscan KJf or Ks Mapped as Franciscan greywacke Platform metagraywacke with Complex (KJfg) based on high magnetic values in albite (?)" aerial survey data, could be Cretaceous Sandstone D28/$7 11/8/1989 Santa Rosa "Fine-gr, tuffaceous Obispo Tmor Stratigraphic position above basal Platform sandstone" Formation(?)
Tertiary contact (recognized in (To) bathymetric data) is consistent with resistant subunit of Obispo Formation D28/S8 11/8/1989 Santa Rosa "Fine- to med-gr, Obispo Tmor Stratigraphic position above basal Platform tuffaceous, vesicular Formation(?)
Tertiary contact (recognized in Shoreline Fault Zone Report, Appendix B Geology Page B-55 of 112 Table B-2. Diver Samples from LTSP LTISP Sample LTs P U nit, 2 010 Re-Sample Date Location aAdditional Comr*ents[D* Description i hterpretation interpretation sandstone" (To) bathymetric data) is consistent with resistant subunit of Obispo Formation D28/S9 11/8/1989 Santa Rosa "Vesicular, zeolitized Obispo Tmor Stratigraphic position above basal Platform tuff; based on trend Formation (To) Tertiary contact (recognized in of ridges strike" bathymetric data) is consistent with resistant subunit of Obispo Formation D29/S10 11/8/1989 Santa Rosa "Light gray, Squire Member Ks or TolTpp This sample is probably from within Platform moderately of the Pismo Cretaceous Sandstone, but may be indurated, fine-gr, Formation (Tfs) Tertiary-age (Pismo or Obispo sandstone" Formations)
D29/S11 11/8/1989 Santa Rosa "Gray, fine-gr, well- Squire Member Ks or To/Tpp This sample is probably from within Platform sorted sandstone" of the Pismo Cretaceous Sandstone, but may be Formation (Tps) Tertiary-age (Pismo or Obispo Formations)
D29/S12 11/8/1989 Santa Rosa "Very dark brown Monterey Ks or To/Tpp This sample is probably from within Platform mudstone, laminated Formation, Cretaceous Sandstone, but may be with tan blebs < 1 Phosphatic Tertiary-age (Pismo or Obispo mm across" (Tmm) Formations)
D30/S1 11/9/1989 Santa Rosa "Fine- to med-gr, Franciscan KJf or Ks Mapped as Franciscan Complex Platform greywacke" Complex (KJfg) rock based on high magnetic values in aerial survey data, could be Cretaceous Sandstone D30/$2 11/9/1989 Santa Rosa "Dark gray to black, Franciscan KJf or Ks Mapped as Franciscan Complex Platform sheared greywacke Complex (KJfg) rock based on high magnetic values (strike to NE-SW)" in aerial survey data, could be Cretaceous Sandstone D31 /S3 11/9/1989 Santa Rosa "Coarse-gr, Franciscan KJf or Ks Mapped as Franciscan Complex Platform crystalline albite (?), complex (KJfm) rock based on high magnetic values and greenish black, in aerial survey data, could be sheared Cretaceous Sandstone metagraywacke" D31/S4 11/9/1989 Santa Rosa "Orange-brown, Franciscan KJf or Ks Mapped as Franciscan Complex Platform foliated, aphanitic Complex rock based on high magnetic values silica-carbonate 
(?) (KJfm) in aerial survey data, could be rock" Cretaceous Sandstone D31/$5 11/9/1989 Santa Rosa "Weathered/altered Franciscan KJf or Ks Mapped as Franciscan Complex Platform serpentinite" Complex rock based on high magnetic values (KJfm) in aerial survey data, could be Cretaceous Sandstone D32/$6 11/9/1989 Santa Rosa no data no data n/a No sample, not reinterpreted Platform D32/S7 11/9/1989 Santa Rosa "Dark green, med-gr, Unnamed Kv or Tmod Could be Cretaceous volcanic rock Platform diabase" volcanic rock with sandstone, or diabase subunit (Tv'r) of the Obispo Formation D33/S8 11/9/1989 Santa Rosa "Cobble of dark Monterey Ks or To/Tpp This sample is probably from fine-Platform brown, faintly bedded Formation.
grained interbeds within Cretaceous mudstone with Phosphatic 
(?) Sandstone, but may be Tertiary-age abundant forams" (Tmm) (Pismo or Obispo Formations)
D33/$9 11/9/1989 Santa Rosa "Same as Dive 33, Monterey Ks or To/Tpp This sample is probably from fine-Platform Sta. 8" Formation, grained interbeds within Cretaceous Phosphatic 
(?) Sandstone, but may be Tertiary-age (Tmm) (Pismo or Obispo Formations)
Shoreline Fault Zone Report, Appendix B Geology Page B-56 of I I .2 Table B-2. Diver Samples from L TSP Sample Date Location LTSP Sample LTSP Unit 2010 Re- Additional Comments ID*I DeScription Interpretation interpretation D34/$1 11/10/1989 Santa Rosa "Med. to dark brown, Monterey Ks or To/Tpp. This sample is probably from fine-Platform siliceous mudstone Formation grained interbeds within Cretaceous with silica-filled (Tmm) Sandstone, but may be Tertiary-age fractures" (Pismo or Obispo Formations)
D34/S2 11/10/1989 Santa Rosa "Orange-brown, Obispo Tmor Stratigraphic position above basal Platform pyrite dense, hard Formation(?)
Tertiary contact (recognized in tuff with" (To) bathymetric data) is consistent with the resistant subunit of Obispo Formation D34/S3 11/10/1989 Santa Rosa "Black, flow-banded, Unnamed Tmod Stratigraphic position above basal Platform vesicular basalt" volcanic rock Tertiary contact (recognized in (Tvr) bathymetric data) is consistent with the diabase subunit of Obispo Formation D35/S4 11/10/1989 Santa Rosa "Greenish black, Unnamed Tmod Stratigraphic position above basal Platform med. porphyritic volcanic rock Tertiary contact (recognized in diabase to coarse (Tvr) bathymetric data) is consistent with gr" the diabase subunit of Obispo Formation D35/S5 11/10/1989 Santa Rosa "Gray-brown, Obispo Tmor Sample may be slightly mislocated, Platform aphanitic tuff with Formation(?)
stratigraphic position above basal pyrite" (To) Tertiary contact (recognized in 9 bathymetric data) is consistent with the resistant subunit of Obispo Formation D35/$6 11/10/1989 Santa Rosa "Gray-brown, Rincon(?) (Tr), Tmo or Tr Sample may be slightly mislocated, Platform massive siltstone Monterey(?)
stratigraphic position consistent with (could also be (Tmb), or Point Obispo or Rincon Formations Monterey or Pt. Sal. Sal fins.)" formations(?)(Tpsa)D36/S7 11/10/1989 Santa Rosa "Fine- to med-gr Franciscan KJf or Ks Mapped as Franciscan Complex Platform greywacke; near T/K Complex(?)
rock based on high magnetic values ctc., clasts of To, (KJfg), or in aerial survey data, could be diabase observed Cretaceous Cretaceous Sandstone nearby" Sandstone (Ks)D36/$8 11/10/1989 Santa Rosa "Fine-gr greywacke Franciscan KJf or Ks Mapped as Franciscan Complex Platform with abundant lithic Complex(?)
rock based on high magnetic values grains" (KJfg), or in aerial survey data, could be Cretaceous Cretaceous Sandstone Sandstone (Ks)D36/S9 11/10/1989 Santa Rosa "Like Dive 36, Sta. 8 Franciscan KJf or Ks Mapped as Franciscan Complex Platform with scattered, 700 Complex(?)
rock based on high magnetic values SE flattened lithic (KJfg), or in aerial survey data, could be grains" Cretaceous Cretaceous Sandstone Sandstone (Ks)D37/S10 11/10/1989 Santa Rosa "Dark greenish gray, Franciscan KJf or Ks Mapped as Franciscan Complex Platform very fine-gr, highly Complex (KJfg) rock based on high magnetic values sheared greywacke" in aerial survey data, could be Cretaceous Sandstone D38/S1 1 11/10/1989 Santa Rosa "Fine- to med-gr, Franciscan KJf or Ks Mapped as Franciscan Complex Platform greywacke with rare Complex(?)
rock based on high magnetic values lithic clasts; like Dive (KJfg), or in aerial survey data, could be 36, Sta. 7" Cretaceous Cretaceous Sandstone__Sandstone (Ks)Shoreline Fault Zone Report, Appendix B Geology Page B-5 7 of 112 Table B-2. Diver Samples from L TSP Sample 1Date Location LTSP Safmple LTSP Unit 2010 Re-ID* j Description Interpretation interpretation Additional Comments D38/$12 11/10/1989 Santa Rosa "Very fine-gr, Franciscan KJf or Ks Mapped as Franciscan Complex Platform sheared Complex(?)
rock based on high magnetic values micrograywacke; (KJfg), or in aerial survey data, could be shears give rock Cretaceous Cretaceous Sandstone laminated Sandstone (Ks)appearance" D39/S1 11/11/1989 Santa Rosa "Greenish-black, Franciscan Ks or KJf Mapped as Cretaceous Sandstone Platform greywacke fine-gr, Complex (KJfg) based on low magnetic values in sheared" aerial survey data, could be Franciscan Complex rock D39/$2 11/11/1989 Santa Rosa "Yellow-brown, med- Rincon Tmo or Tr Sample may be slightly mislocated, Platform gr sandstone with Formation(?)
stratigraphic position consistent with black shale rip-up (Tr), Vaqueros Obispo or Rincon Formations clasts (turbidite)" sandstone(?)(Tv) (turbidite)
D39/$3 11/11/1989 Santa Rosa "Gray, v. fine- to fine- Obispo Tmor Sample may be slightly mislocated, Platform gr tuff, Formation (To) stratigraphic position consistent with resistant subunit of the Obispo Formation D40/$4 11/11/1989 Santa Rosa "Sheared red chert" Franciscan KXJ Consistent with Franciscan Platform Complex Complex rock mapped along the (KJfm) coastline D40/$5 11/11/1989 Santa Rosa "Serpentinite, plus Franciscan KXJ Consistent with Franciscan Platform low ridge of Complex Complex rock mapped along the pervasively sheared (KJfm) coastline black shale" D40/$6 11/11/1989 Santa Rosa "Serpentinite, Sta. 5 Franciscan KXJ Consistent with Franciscan Platform same as Dive 40" Complex Complex rock mapped along the (KJfm) coastline D41/S7 11/11/1989 Santa Rosa "Massive, dark, fine- Franciscan Ks or KXJ Mapped as Cretaceous Sandstone Platform gr greywacke with Complex(?)
based on low magnetic values in rare crystal-lined (KJfg), or aerial survey data, could be vugs". Cretaceous Franciscan Complex rock Sandstone (Ks)D41/S8 11/11/1989 Santa Rosa "Gray, v. fine-gr. to Obispo Tmor Stratigraphic position above basal Platform aphanitic tuff, with Formation(?)
Tertiary contact (recognized in scattered phenos, (To) or Cambria bathymetric data) is consistent with zeolitized pumice; Felsite the resistant subunit of Obispo possible depositional Formation KfIT contact" D41/$9 11/11/1989 Santa Rosa "Gray, very fine-gr, Obispo Tmor Stratigraphic position above basal Platform slightly vesicular tuff, Formation (To) Tertiary contact (recognized in zeolite-lined vugs" bathymetric data) is consistent with the resistant subunit of Obispo Formation D41/S10 11/11/1989 Santa Rosa "Dark gray, massive Rincon Tmor Stratigraphic position above basal Platform mudstone (Dive 41, Formation(?)
Tertiary contact is consistent with Sta. 8 -10 crossed (Tr) interbedded tuff and siltstone as synclinal axis)" observed onshore in subunit Tmor of the Obispo Formation 51 9/19/1986 San Luis "Gry to tan tuff" Tmor Tmor Stratigraphic position above basal Bay Tertiary contact (recognized in bathymetric data) is consistent with the resistant subunit of Obispo Formation Shoreline Fault Zone Report, Appendix B Geology Page B-58 of 112 Table B-2. Diver Samples from L TSP S I ample Date -7 Location LTSP Sample LTSP Unit 2010 Re- Additi nI Comments ID* Description Interpretation inteipretation A na 52 9119/1986 San Luis "wht tuff" Tmot Tmot Consistent with tuffaceous subunit Bay of Obispo Formation mapped along the coastline 53 9/19/1986 San Luis "blk sit" Tmr Tr Sample may be slightly mislocated, Bay consistent with Rincon Formation mapped along the coastline northwest of the Wilmar Avenue fault 54 9/19/1986 San Luis "md gr diabase" Tmod Tmod Consistent with diabase subunit of Bay Obispo Formation mapped along the coastline southeast of the WilmarAvenue fault 55 9/19/1986 San Luis "md-fngr diabase" Tmod Tmod Consistent with diabase subunit of Bay Obispo Formation mapped along the coastline southeast of the Wilmar Avenue fault 56 9/19/1986 San Luis "md-fn gr diabase" Tmod Tmod Consistent with diabase subunit of Bay Obispo Formation mapped along the coastline southeast of the Wilmar Avenue fault 57 9/19/1986 San Luis "gry diabase" Tmod Tmod Consistent with diabase subunit of Bay Obispo Formation mapped along the coastline southeast of the Wilmar Avenue fault 58 9/19/1986 San Luis "dk gry-grn diabase" Tmod Tmod Consistent with diabase subunit of Bay Obispo Formation mapped along the coastline southeast of the Wilmar Avenue fault 59 9/19/1986 San Luis "gry blk sit" Tmr Tr Sample may be slightly mislocated, Bay consistent with Rincon Formation mapped along the coastline northwest of the Wilmar Avenue fault 60 9/19/1986 San Luis "gry-grn diabase" Tmod Tmod Consistent with diabase subunit of Bay Obispo Formation mapped along the coastline northwest of the V Wilmar Avenue fault 61 9/19/1986 San Luis "diabase" Tmod Tmod Consistent with diabase subunit of Bay Obispo Formation mapped along the coastline northwest of the Wilmar Avenue fault 62 9/19/1986 San Luis "wht tuff, might be Tmo/Tmor?
Tmot/Tmor Consistent with tuffaceous or Bay somewhat calcified" resistant subunit of Obispo Formation mapped along the coastline northwest of the Wilmar Avenue fault 63 9/19/1986 San Luis "It brn tuff, might be Tmo/Tmor?
Tmot/Tmor Consistent with tuffaceous or Bay slight sil." resistant subunit of Obispo Formation mapped along the coastline northwest of the Wilmar Avenue fault 64 9/19/1986 San Luis "gry tuff, might be Tmo/Tmor?
TmotlTmor Consistent with tuffaceous or Bay slight sil. or calcified" resistant subunit of Obispo Formation mapped along the coastline northwest of the Wilmar_Avenue fault Shoreline Fault Zone Report, Appendix B Geology Page B-59 of 112 Table B-2. Diver Samples from L TSP Sample LTSP Sample LTSP Unit 2010 Re-ID* Date Location Description Interpretation interpretation 65 9/19/1986 San Luis "gry blk sit" Tmr Tr Sample may be slightly mislocated, Bay consistent with Rincon Formation mapped alongthe coastline northwest of the Wilmar Avenue fault 66 9/19/1986 San Luis "dk-gry diabase" Tmod Tmod Consistent with diabase subunit of Bay Obispo Formation mapped along the coastline northwest of the Wilmar Avenue fault 67 9/19/1986 San Luis "gry tuff" Tmot Tmot Consistent with tuffaceous subunit Bay of Obispo Formation mapped along the coastline 68 9/19/1986 San Luis "Lt gry tuff" Tmot Tmot Consistent with tuffaceous subunit Bay of Obispo Formation mapped along the coastline 69 9/19/1986 San Luis "gry tuff" Tmot Tmot Consistent with tuffaceous subunit Bay of Obispo Formation mapped along.T__ _ the coastline 70 9/19/1986 San Luis "lam gry-blk sft sit to Tmo/Tmm? Tmo Consistent with Obispo Formation Bay dk bin sh" mapped along the coastline 71 9/19/1986 San Luis "gry-blugry tuff" Tmot Tmot Consistent with tuffaceous subunit Bay of Obispo Formation mapped along the coastline 72 9/19/1986 San Luis "gry, hard fin gr tuff' Tmot Tmot Consistent with tuffaceous subunit Bay of Obispo Formation mapped along the coastline 73 9/19/1986 San Luis "gry tuff" Tmot Tmot Consistent with tuffaceous subunit Bay of Obispo Formation mapped along the coastline 74 9/19/1986 San Luis "gry sil cavities fin gr Tmor Tmot/Tmor Consistent with tuffaceous or Bay tuff, resistant subunit of Obispo Formation mapped along the coastline northwest of the Wilmar Avenue fault 75 9/19/1986 San Luis "gry blk soft sit to dk Tmo Tmor/Tmof Stratigraphic position is consistent Bay brn sh" with resistant or fine-grained subunits of Obispo Formation 76 9/19/1986 San Luis "blu gry masshrd fine Tmot/Tmo Tnmo Consistent with Obispo Formation Bay gr tuff, could be fine mapped along the coastline gr ss" 77 9/19/1986 San Luis "blu gry tuff' Tmot TmotlTmor Consistent with tuffaceous or Bay resistant subunit of Obispo Formation mapped along the coastline 78 9/19/1986 San Luis "gry bin Sit, blocky Tmo Tmor/Tmof Stratigraphic position is consistent Bay fract, hard" with resistant or fine-grained subunits of Obispo Formation 79 9/19/1986 San Luis "Blu gra fn gr sit, Tmo/Tmot Tmor/Tmof Stratigraphic position is consistent Bay could be tuff" with resistant or fine-grained subunits of Obispo Formation 80 9/19/1986 San Luis "gry hard mass v fine Tmo Tmor/Tmof Stratigraphic position is consistent Bay gr ss/slt" with resistant or fine-grained subunits of Obispo Formation 81 9/19/1986 San Luis "blu gry tuff" Tmot TmotlTmor Consistent with tuffaceous or Bay resistant subunit of Obispo Formation mapped along the Shoreline Fault Zone Report, Appendix B Geology Page B-60 ofl112 Table B-2. Diver Samples from L TSP Sample Date Location LTSP Sample LTSP Unit 1010 Re- Additional Comments IDescription Interpretation interpretation coastline 82 9/19/1986 San Luis "blu-gry fine gr tuff Tmo TmorlTmof Stratigraphic position is consistent Bay w/xls" with resistant or fine-grained subunits of Obispo Formation 83 9/19/1986 San Luis "It gry brn silt/sh; not Tmm Tmor/Tmof or Stratigraphic position is consistent Bay typical of Tmm" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 84 9/19/1986 San Luis "It gry to brn lam Tmm Tmor/Tmof or Stratigraphic position is consistent Bay slt/sh" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 85 9/19/1986 San Luis "Lt gry blk sit" Tmm Tmor/Tmof or Stratigraphic position is consistent Bay Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 86 9/19/1986 San Luis "brn silty sh; similar Tmm Tmor/Tmof or Stratigraphic position is consistent Bay to sample 83" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 87 9/19/1986 San Luis "fry to blk lam sdy sh" Tmm Tmor/Tmof or Stratigraphic position is consistent Bay Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 88 9/19/1986 San Luis 'gry bin fossil sndy? Tmm Tmor/Tmof or Stratigraphic position is consistent Bay sit/sh" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 89 9/19/1986 San Luis "blk lam sh" Tmm Tmor/Tmof or Stratigraphic position is consistent Bay Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 90 9/19/1986 San Luis,. "blk sil sh highly Tmm Tmor/Tmof or Stratigraphic position is consistent Bay fractured" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 91 9/19/1986 San Luis "blk lam sit sh" Tmm TmorlTmof or Stratigraphic position is consistent Bay Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 92 9/19/1986 San Luis "blk lam sil sh" Tmm Tmor/Tmof or Stratigraphic position is consistent Bay Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 93 9/19/1986 San Luis "It gry to bin lam sil Tmm Tmor/Tmof or Stratigraphic position is consistent Bay sh" Tmm with resistant or fine-grained subunits of Obispo Formation, could___be Monterey Formation 94 9/19/1986 San Luis "It and dk gry lam sil Tmm Tmor/Tmof or Stratigraphic position is consistent Bay sh/slt" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 95 9/19/1986 San Luis "It gry lam sh; slightly Tmm TmorlTmof or Stratigraphic position is consistent Bay sil and locally Tmm with resistant or fine-grained dolomitic" subunits of Obispo Formation, could Shoreline Fault Zone Report, Appendix B Geology Page B-61 of 112 Table B-2. Diver Samples from L TSP Date LTSP Sample LTSP Unit 2010 Re- ommehts ID* ocaio Desiptn Interpretation iilterpretation Additional be Monterey Formation 96 9/19/1986 San Luis "It and dk lam sh and TmpmFTmm?
TmorlTmof or Stratigraphic position is consistent Bay v. fn gr ss" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 97 9/19/1986 San Luis "dk gry slightl sndy Tmpm TmorlTmof or Stratigraphic position is consistent Bay sit" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 98 9/19/1986 San Luis "gry and bin massive Tmpm TmorlTmof or Stratigraphic position is consistent Bay sit" Tmm with resistant or fine-grained subunits of Obispo Formation, could be Monterey Formation 99 9/19/1986 San Luis "gry to wht tuff, Tmpm TmorlTmof or Stratigraphic position is consistent Bay surrounded by 'ided' Tmm with resistant or fine-grained Tpp" subunits of Obispo Formation, could be Monterey Formation 100 9/19/1986 San Luis "dk gry mass slt/sh; Tmpm Tmor/Tmof or Stratigraphic position is consistent Bay also in bag is soft dk Tmm with resistant or fine-grained
-fn gr ss" subunits of Obispo Formation, could be Monterey Formation 101 9/19/1986 San Luis "gry mass f gr tuff ss" Tmpm TmorlTmof Stratigraphic position is consistent Bay with resistant or fine-grained subunits of Obispo Formation 102 9/19/1986 San Luis "It gry to blue sil tuff" Tmor TmotlTmor Consistent with tuffaceous or Bay resistant subunit of Obispo Formation mapped along the coastline 103 9/19/1986 San Luis "dk gry blk, gry brn sh Tmo Tmor/Tmof Stratigraphic position is consistent Bay (tar on jts)" with resistant or fine-grained
:subunits of Obispo Formation 104 9/19/1986 San Luis "gry bin hard sil sltor Tmm Tmor/Tmof or Consistent with resistant or fine-Bay Tuff" Tmm grained subunits of Obispo Formation mapped alongthe coastline, could be Monterey Formation 105 9/19/1986 San Luis "dk gry fn gr ss, hard" Tmo Tmot/Tmor Consistent with tuffaceous or Bay resistant subunit of Obispo Formation mapped along the coastline 106 9/19/1986 San Luis "gry-wht tuff, hard" Tmor Tmot/Tmor Consistent with tuffaceous or Bay resistant subunit of Obispo (onshore?)
Formation mapped along the coastline 107 9/19/1986 Santa Rosa "dk gry to gin KJfmv KJf Consistent with Franciscan Platform aphanitic, meta Complex rock mapped along the volcanic or qtz mix" coastline 108 9/19/1986 Santa Rosa "dk gry to grn KJfmv KJf Mapped as Franciscan Complex Platform aphanitic grnstn" rock based on high magnetic values in aerial survey data 109 9/19/1986 Santa Rosa "gry gin med gr ss" Ks Ks Consistent with Cretaceous Platform Sandstone mapped along the coastline Shoreline Fault Zone Report, Appendix B Geology Page B-62 of 112 Table B-2. Diver Samples from L TSP Sample Date Location LTSP Sample LTSP Unit 2010 Re- Additional Comments Description Interpretation interpretation, 110 9/19/1986 Santa Rosa "grnstn" KJfmv KJf Mapped as Franciscan Complex Platform rock based on high magnetic values in aerial survey data 111 9/19/1986 Santa Rosa "gry bn to gry gin KJfmv KJf Mapped as Franciscan Complex Platform metavolcanic" rock based on high magnetic values in aerial survey data 112 9/1 9/1986 Santa Rosa gry gi cr gr ss" Ks?/KJfss?
KJf Mapped as Franciscan Complex Platform rock based on high magnetic values in aerial survey data 113 9/19/1986 Santa Rosa "Wht tuff, fn gr" Tmot Tmor Consistent with resistant subunit of Platform Obispo Formation mapped at Crowbar 114 9/19/1986 Santa Rosa "grn med-fn gr tuff' Tmot Tmor Consistent with resistant subunit of Platform Obispo Formation mapped at Crowbar 115 9/19/1986 Santa Rosa "Diabase" Tmod Tmod Consistent with resistant subunit of Platform Obispo Formation mapped at Crowbar and with high magnetic values in aerial survey data 116 9/19/1986 Santa Rosa "dk gry biotite tuff" Tmor Tmor Consistent with resistant subunit of Platform Obispo Formation mapped at Crowbar Shoreline Fault Zone Report, Appendix B Geology Page B-63 of 112 Table B-3. Diver Samples Collected July 2010 Table B-3. Diver Samples Collected July 2010 Sample ID* Date Location Sample Description Unit ID DS001 7/12/2010 Santa Rosa Dark grayish brown sandy SILTSTONE Ks (fine-gr)Platform Santa Rosa Greenish gray METAMORPHIC ROCK and DSO02 7/12/2010 Platform light bluish gray SANDSTONE Kjf DS003 7/12/2010 Santa Rosa GaihbonSNTOEKS PlatformGrysbrwSADTN Santa Rosa DS004 7/12/2010 Platform Light brown sandy MUDSTONE Ks (fine-gr)Santa Rosa LgtbonsnyMDTN s(ieg DS005 7/12/2010 SataRosa Medium gray SANDSTONE Ks DS005 7/122010 Platform DS006 7/2/2010 Santa Rosa Dark gray VOLCANIC ROCK Ks/Kv Platform Santa Rosa DS07 712200 Platform Grayish brown SANDSTONE K DS008 7/12/2010 Platform Dark grayish brown silty SANDSTONE Ks (fine-gr)D09 71/00 Santa Rosa Light gray SANDSTONE Tmor Platform Santa Rosa DS010 7/12/2010 Santa Rosa Orange brown TUFF Tmor Platform DS01 1 7/12/2010 Santa Rosa Medium gray SANDSTONE Ks Platform DS012 7/12/2010 Santa Rosa Dark gray VOLCANIC ROCK KJfmv Platform DS013 7/12/20i0 Santa Rosa 7/12/2010 Platform Grayish brown SANDSTONE Ks Shoreline Fault Zone Report, Appendix B Geology Page B-64 of l112 Table B-3. Diver Samples Collected July 2010 Sample ID* Date Location Sample Description Unit ID DS014 7/12/2010 Santa Rosa Grayish brown SANDSTONE Ks Platform DS015 7/12/2010 Santa Rosa Grayish brown SANDSTONE Ks Platform DS016 7/12/2010 Santa Rosa Medium gray TUFF Tmor Platform DS017 7/13/2010 Santa Rosa Dark greenish brown VOLCANIC ROCK KJfmv Platform Santa Rosa DS018 7/13/2010 Platform Dark greenish gray VOLCANIC ROCK KJfmv DS020 7/13/2010 Santa Rosa Dark greenish gray VOLCANIC ROCK KJfmv Platform DS021 7/13/2010 Santa Rosa Dark gray SaNDSONE Ks Platform DS022 7/13/2010 Santa Rosa Grih gray SANDSTONE Ks Platform DS023 7/13/2010 Santa Rosa Grayish brown SANDSTONE Ks Platform DS024 7/13/2010 Plantafosa 
' Darkh grayis rw SANDSTONE Ks DS025 7/13/2010 Santa Rosa Greenish gray METAMORPHIC ROCK Klf Platform DS026 7/13/2010 Santa Rosa Dark grayish brown sandy SILTSTONE Ks (fine-gr)Platform Shoreline Fault Zone Report, Appendix B Geology Page B-65 of 112 Table B-3. Diver Samples Collected July 2010 Sample ID* Date Location Sample Description Unit ID DS027 7/14/2010 Santa Rosa Dark grayish brown sandy SILTSTONE TmoflTmor Platform Santa Rosa DS029 7/14/2010, Santa Rosa Olive brown SANDSTONE Ks Platform DS030 7/14/2010 Santa Rosa Dark brown sandy SILTSTONE Tmof/Tmor Platform DS031 7/14/2010 Santa Rosa Dark brown sandy SILTSTONE Tmof/Tr Platform DS032 7/14/2010 Santa Rosa Greenish gray METAMORPHIC ROCK KJf Platform DS033 7/14/2010 Santa Rosa Dark bluish green VOLCANIC ROCK KJfmv Platform DS034 7/14/2010 Santa Rosa Medium gray SANDSTONE Ks Platform DS036 7/14/2010 Santa Rosa Greenish gray METAMORPHIC ROCK KJf Platform DS036 7/15/2010 Santa Rosa Dark bluish green VOLCANIC ROCK KJfmv Platform DS037 7/15/2010 Santa Rosa Grayish brown SANDSTONE Ks Platform DS038 7/15/2010 Santa Rosa Very dark gray sheared CLAYSTONE KJfm Platform DS039 7/15/2010 Santa Rosa Dark gray SANDSTONE Ks Platform I Shoreline Fault Zone Report, Appendix B Geology Page B-66 of 112 Table B-3. Diver Samples Collected July 2010 Sample ID* Date Location Sample Description Unit ID 05040 715/2010 Santa Rosa K DS040 7/15/2010 Platform Grayish brown SANDSTONE Ks DS041 7/15/2010 Santa Rosa, Dark gray SANDSTONE Ks Platform Santa Rosa DS042 7/15/2010 Platform Dark gray SANDSTONE Ks DS043 7/15/2010 Santa Rosa Dark gray SANDSTONE Ks Platform DS044 7/15/2010 Santa Rosa Dark brown sandy SILTSTONE Ks (fine-gr)Platform DS045 7/15/2010 Santa Rosa ARTIFICIAL FILL AF Platform DS046 7/17/2010 San Luis Bay Greenish and reddish brown VOLCANIC ROCK KJfmv DS047 7/17/2010 San Luis Bay Greenish gray METAMORPHIC ROCK KJf DS048 7/17/2010 San Luis Bay Grayish brown SANDSTONE Ks DS049 7/17/2010 San Luis Bay Greenish and reddish brown VOLCANIC ROCK KJfmv DS050 7/17/2010 San Luis Bay Grayish brown SANDSTONE Ks DS051 7/17/2010 San Luis Bay Greenish gray VOLCANIC ROCK KJfmv oreline Fault Zone Report, Appendix B Geologic Map Shoreline Fault Zone Report, Appendix B Geology Page B-67 of 87 Page B-67 of 112 0 TABLE B-4 Characteristics of the N40W fault.0 0 Location /fault Seismicity Geomorphic (Bathymetric)
Litholo Structure Potential Field Characteristics Expression Location No clearly associated Fault crosses the Islay shelf Fault cuts Fault truncates structures and strata of No gravity seismicity lineament, without apparent vertical offset. Miocene strata Obispo, Monterey and Pismo Formations.
anomaly at south Offshore of Point but northern sub- (Obispo, end, but north end Buchon to Lion lineament may connect Moderate geomorphic Monterey, lower Middle part where exposed on wave-cut of fault follows Rock up-dip to N40W fault. expression.
North part has Pismo platform west of Crowbar is straight north plunge of discontinuous straight fault-line Formations).
lineament juxtaposing contrasting Obispo gravity high in the Strike, Dip Epicenters of about 7 scarps accented by paleo-sea rock units. Consists of two traces in zone northern Islay events associated with cliffs in contact with sand sheets. South part 50 meters wide. shelf.N40OW the southern end of the Central part is a lineament in covered by sand (N35 0-44&deg;W), 900 North segment exposed Obispo Formation sheet but inferred The fault may be imaged in several high- Follows the east Shoreline fault occur at rocks. South part covered by to be contact resolution seismic-reflection profiles along side of a prominent Length the south end of the sand sheet west of Crowbar Hill. between Obispo middle and south part, but evidence is magnetic high in N40W fault and two Formation ambiguous.
the north; crosses 7 to 8 km events plot near the Pleistocene wave-cut platform in sedimentary rock the high and central part of the fault. Obispo Formation rocks crosses on west with North end is covered with sand sheet but follows the west Width. fault with no vertical separation Obispo diabase continues along the 'linear' margin of the side of the anomaly (down dip) of platform with an uncertainty on east based on rocky platform for up to 3 km. in the south.of about 2 meters. magnetic field. Magnetic high 12 km (+3/-2 kin) Deep seismic-reflection profiles (from believed to be LTSP) may show north end of fault. associated with Activity offshore Point Buchon where N40W fault Obispo diabase.intersects previously identified "Crowbar" Possible evidence faults.of late Quaternary activity because of South part interpreted to continue beneath (1) probable sand sheet for 2 km along magnetic structural gradient west of Lion Rock. It may connection to connect with the Central segment (C-I) of Central segment the Shoreline fault zone where the two and (2) possible faults have a 250 strike difference.
association with Alternatively, the fault may splay to the seismicity east and end west of Lion Rock.lineament Shoreline Fault Zone Report, Appendix B Geology Page B-68 of 112 e e e TABLE B-5 Characteristics of the North segment of the Shoreline fault zone.Location / Fault Gomorphic (Bathymetric) 
-Chratritis Seismicity 
' (aymtc) Lithology Structure Potential Field Characteristics ExpressionLih1gStuur Location Sub-lineament is 8 km No surface expression in Inferred offset in Distinct from N40W fault. Northern end long, 2 to 15 km deep. Quaternary sediments that Miocene rocks tenninates within Northwest end is overlie bedrock on the Islay (Obispo or Two short en-echelon faults cutting steep gravity the Hosgri fault A reverse and a shelf. Monterey Miocene strata tentatively interpreted in gradient associated zone west of Point composite right-lateral Formation) in shallow seismic lines: the southwestern with Hosgri fault Buchon; southeast focal mechanism for high-resolution fault may offset the core of a syncline zone.end is Lion Rock. events at the north end seismic- (northeast-side down vertical separation);
and two right-lateral reflection the northeastern fault may offset the east Fault is between Strike, Dip focal mechanisms near profiles.
limb of the syncline (also northeast-side linear magnetic Lion Rock. down vertical separation).
Deep seismic intensity highs.N45&deg;W, 90. line at the north end of the segment, near the intersection with the Hosgri fault zone, Length shows the absence of faulting within the resolution of the seismic line.Up to 8 km Width (down dip)12 km (+3/-2 kin)Activity Treated as active because of associated seismicity lineament.
Shoreline Fault Zone Report, Appendix B Geology Page B-69 of 112 e e e TABLE B-6 Characteristics of the Central segment of the Shoreline fault zone.Location / Fault Geomorphic*(Bathymetric)
S Characteristics "Seismicity Expression Lithology Structure Potential Field Location Prominent to moderately Fault located Fault segment consists of three Fault follows prominent geomorphic within melange geomorphically and structurally defined strong linear Lion Rock to west Two earthquakes near expression, with fault-line scarps in middle and sub-segments C-i- C-2, and C-3 (see magnetic high that of Rattlesnake Cr. Green Peak have right- in resistant rock units, shallow south parts. separate tables below), lies within the lateral focal troughs, and lineament in Franciscan Strike, Dip mechanisms; another melange. Faultjuxtaposes Sub-segments C-3 and C-2 are separated m6lange except at earthquake has an Obispo diabase by a 50 to 150 meter right stepover and northern end where N65&deg;W, 90&deg; oblique right-lateral Locally sharp morphology with against sub-segments C-2 and C-I appear to merge fault coincides with reverse focal right-stepping, en-echelon Franciscan with a change in strike, a magnetic low.Length mechanism, and a traces. m~lange in north composite focal part. North end buried by sand sheet but trends 7 to 9 km mechanism yields a toward the North segment; alternatively, right-lateral solution.
central segment may merge with the Width N40W fault with 250 difference in strike.(down dip)8 to 10 km South end defined by an east-trending (seismicity sub- splay that trends toward the onshore lineament)
Rattlesnake fault (San Luis Bay fault zone). Alternatively, Central segment dies Activity out in sand sheet south of Rattlesnake Creek.Treated as active because of Central and South segments either merge association with with a 40 strike change or are separated by seismicity a right step of up to 400 to 500 meters lineament; beneath the sand sheet that covers the possible i-meter- north part of the South segment.high fault scarp in-75,000 wave-cut Age of faulting is post middle Miocene.platform.Shoreline Fault Zone Report, Appendix B Geology Page B-70 of 112 e 0 0 TABLE B-6 (continued).
Sub-segment C-1, Central segment of the Shoreline fault zone.Location /sFault Seismici Geomorphic (Bathymetric)
Lithology Structure haatrsisty Expression Potential Field Location of C-1 Moderately prominent, linear Sub-segment is Sub-segment truncates bedding. North end where southwest-facing fault-line scarp the contact buried by Lion Rock to approximately 5 meters high on between Obispo South end partly covered by sand sheet and sediments sub-Green Peak east side of fault with sand sheet Formation appears to merge with north end of C-2 segment follows a and scattered rocks to southwest.
diabase and with an 8' change in strike offshore of the magnetic low.Strike, Dip Obispo resistant Intake Cove, or may end with right Follows shallow trough and tuff to the east stepover of 15.0 meters. Alternatively, but Sub-segment N68&deg;W, 900 generally covered with sand and Franciscan unlikely, the south end may change strike crosses magnetic sheet with local rock streaks m6lange(?)
and trend onshore west of Green Peak. high interpreted to Length parallel to fault protruding above containing be Obispo diabase sand. numerous A north-south fault imaged in the magnetic on the northeast 1.8 to 3.4 km knockers to the field data in bedrock at the Discharge Cove and Franciscan Shallow seismic-reflection west along a does not appear displaced but 100 to 200 m6lange on profiles show a Pleistocene zone generally meters displacement is permissible.
southwest.
wave-cut platform (> 75 ka) with covered by sand Estimated slip rate in past is less than I to a m-high scarp that is sheet. 2 million years is 0.05 to 0.2 mm/yr North part follows interpreted as erosional but may the east flank of a be from northwest-sideup fault magnetic high displacement.
interpreted to be m6lange.Sub-segment C-2 is interpreted to cross a Pleistocene wave-cut platform and merge with sub-segment C-I from high-resolution seismic-reflection lines west of Intake Cove.Shoreline Fault Zone Report, Appendix B Geology Page B-71 of`,I 12 T 0 TABLE B-6 (continued).
Sub-segment C-2, Central segment of the Shoreline fault zone.0 Location / Fault Geomorphic (Bathymetric)
LSPotential Field Characteristics Expression Location of C-2 North part has moderate to locally In the north part, North part is generally straight, striking C-2 fault follows a strong expression as a shallow trough sub-segment is N61 0 W, in zone of m6lange containing strong linear Green Peak to and as a wide half-trough with small the contact small resistant knockers; separates magnetic high Olson Hill rocks within the zone; fault lies west between Obispo Cretaceous sandstone from Franciscan within Franciscan of a bedrock scarp and where diabase and m6lange; analysis of shallow seismic data melange.Strike, Dip constrained-is 15 to 20 meters wide; mdlange indicates that the north end continues on generally covered with sand sheet in strike beneath the sand sheet and merges Analysis of N65-W (N43o. trough. In the south part, with sub-segment C-i offshore of the magnetic anomaly 62-W), 900 sub-segment is Intake Cove. gradient indicates South of the DCPP entrance the the contact that fault likely has Length Pleistocene wave-cut platform ( > 75 within m6lange Middle part is straight, strikes N68W; a steep dip.ka) crosses sub-segment C-2 and and between truncates bedding and bedrock faults 4.5 to 5.8 kin shows no vertical separation within Cretaceous 1.5 meters resolution, sandstone and South end may branch into several splays, m6lange. one of which strikes easterly toward the In the south part, west of Olson Hill, late Quaternary deformation zone at Olson.sub-segment has strong geomorphic Hill that is part of the San Luis Bay fault expression as a shallow, 2- to 4- zone; the other may continue south for 130 meter-deep, 25-meter-wide trough. meters on strike following a narrow trough A moderate to strong, 900-meter-long generally in Cretaceous sandstone.
lineament is located within m6lange.Shoreline Fault Zone Report, Appendix B Geology Page B-72 of 112 e TABLE B-6 (continued).
Sub-segment C-3, Central segment of the Shoreline fault zone.Location / Fault -Seismicity Geomorphic (Bathymetric)
Lithology Structure Potential Field Characteristics Expression Location of C-3 Weak to moderate expression as Sub-segment is Middle part is moderately straight, 2.6 km Northern end of a shallow trough bounded by the contact along long, strikes N55&deg;to 62'W; the south end sub-segment West of Olson alignment of small rock knockers the trough may change strike gradually to N70 0 E; crosses west-Hill to west of within the zone. between fault appears to lie within a narrow zone of trending magnetic Rattlesnake Creek. Cretaceous m6lange with only small knockers.
low; southern part Southeast end (intersection with sandstone and of fault follows Strike, Dip Rattlesnake fault) has strong to m6lange South end of sub-segment splays into two steep magnetic moderate expression as a fault- containing traces: one splay continues southeast along gradient that curves N57-W (N43'- line scarp and a shallow, numerous strike for 400 meters before becoming along the eastern 62 0 W), 900 approximately 5-meter-deep, 25- greywacke covered by a sand sheet; the other splay splay toward meter-wide trough. Prominent knockers, curves easterly toward the Rattlesnake Rattlesnake Creek Length paleostrandline is controlled by fault (San Luis Bay fault zone). where magnetic the fault, but no lineament is Southeast end is high ends; the fault 2.4 to 3.5 km detected within deposits (talus within is interpreted to and paleo-beach sediments) at Cretaceous separate the base of the submerged cliff, sandstone.
Cretaceous sandstone from greenstone and supports the interpretation that the fault changes strike easterly.Shoreline Fault Zone Report, Appendix B Geology Page B-73 of 112 TABLE B-7. Characteristics of the South segment of the Shoreline fault zone.0 Location / Fitilt' Gexpression Rihycrc Characteristics Seismicity E r hic (Bathymetric)
Lithology Structure Potential Field Location Weakest expression of Fault traverses the wide, flat Fault.generally North part of fault lies beneath sand sheet. North part of three segments.
Has Santa Rosa Reef shelf. covered by sand Fault either is continuous with south end segment coincides West of trend that is 10' to 15' sheet but of the Central segment or is located to the with subparallel Rattlesnake Creek more westerly than the North part covered by wide inferred to lie west where it would have a right step of linear magnetic to south of Point associated bedrock sand sheet, location uncertain, within 400 to 500 m to the Central segment. highs.San Luis. fault. Franciscan Middle part has moderate m6lange. South part of fault is in a narrowzone of Middle part of the Strike, Dip Largest event (ML 3.5) expression; near south end the Franciscan m6lange; trend is generally segment follows is part of a cluster of fault occupies a shallow, -5 In places fault straight over 21/2 to 3 km near the south the southwest side N47 0 W four events at the meter deep, 50 meter wide forms the end. of a linear (N43 0-50 0 W), 900 southeast end. trough, but to north the fault is lithologic magnetic high.marked by a linear fault-line contact between Locally sharp truncation of rock and strata Length Composite focal scarp between resistant Cretaceous on west side of fault and slices of bedrock mechanism is right sandstone and sand sheet. sandstone and parallel to fault within the m6lange. Rock 6 to 7 km lateral; one earthquake Franciscan structure southeast of Point San Luis yields normal focal Near south end a Pleistocene m6lange. terminates at fault.Width mechanism, wave-cut platform and (down dip) strandline 
(> 75 ka) cross the South end projects beneath sand sheet fault and are not displaced near the seismicity cluster. Ambiguous 8 to 10 km vertically within -1.5 meter evidence for continuation of fault to (seismicity sub- resolution.
southeast on high-resolution seismic-lineament) reflection profiles.South end covered by sand Activity sheet. Age of faulting is post Cretaceous.
Treated as active because of association with seismicity lineament.
oreline Fault Zone Report, Appendix B Geologic Map Shoreline Fault Zone Report, Appendix B Geology Page B-74 of 87 Page B-74 of 112 ATTACHMENT 1- 2010 DIVE SAMPLE DESCRIPTIONS Below are the detailed descriptions of the samples collected with Andy Lutz, FUGRO-William Lettis & Associates, in July 2010 by divers in the Shoreline fault zone study area.Sample ID: DS001 Collected:
07/12/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.18836 W120.82535 (WGS84)Sandy siltstone, dark grayish brown, visible grains in silty matrix are fine-grained, subangular, quartz or carbonate (very slight reaction to HCI). Stratification defined by thin (I to 2 mm) discontinuous fine-grained sand laminations.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures and does not part readily along lamination planes. Sample is fine-grained and may be suitable for microfossil analysis.Notes: Sample collected from a low-relief outcrop with no prominent indication of bedding or jointing.Interpretation:
Fine-grained variant of Cretaceous Sandstone (Ks)Sample ID: DS002 Collected:
07/12/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.18914 W120.82446 (WGS84)This sample includes two different lithologies Metamorphic rock, greenish gray, medium-grained with weakly developed foliation.
Crystal composition dominantly quartz and feldspar with common pyrite and trace chlorite.
Rock is strong (multiple hammer blows to fracture) with few fractures.
Trace fine (1 to 2 mm) quartz veins.Also: Sandstone, light bluish gray, fine- to medium-grained, subangular, dominantly quartz grains with minor feldspar and lithic grains. Samples are unstratified and shear fabric, joints, and fractures are not present. Rock is strong (multiple hammer blows to fracture) with few fractures.
Notes: Sample collected from a low-relief area below a high escarpment; thick kelp created very low visibility conditions.
Interpretation:
Franciscan Complex, melange with greywacke and greenschist metamorphic rock (KJf)Sample ID: DS003 Collected:
07/12/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.18780 W120.82180 (WGS84)Sandstone, grayish brown, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar, carbonate cement (vigorous reaction to HC1). Weakly expressed laminations are defined by grain size variation.
Rock is strong (multiple hammer blows to fracture) with few fractures, no veins, and does not part regularly along lamination planes. Not suitable for microfossil analysis.Notes: Sample collected from prominent hog-back ridges oriented roughly normal to the coastline (i.e., east-west).
Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS004 Collected:
07/12/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.18459 W120.81917 (WGS84)Shoreline Fault Zone Report, Appendix B Geology Page B-75 of 112 Mudstone, sandy, light brown, visible grains in muddy matrix are very fine-grained, subangular, quartz (no reaction to HCI). Weakly expressed laminations are defined by grain size variation.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow), unfractured, no veins, and does not part readily along lamination planes. Possibly suitable for microfossil analysis.Notes: Sample collected from prominent hog-back ridges, orientation information not available.
Interpretation:
Fine-grained variant of Cretaceous Sandstone (Ks), possibly fine-grained subunit of Obispo Formation (Tmof)Sample ID: DS005 Collected:
07/12/20 10, Diver. Carson Porter Location:
Santa Rosa shelf, N35.18093 W120.80783 (WGS84)Sandstone, medium gray, fine- to medium-grained.
Dominantly subangular quartz and lithic grains with minor feldspar, minor carbonate cement (very slight reaction to HCI). Weakly expressed laminations are defined by grain size variation.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures, no veins, and does not part regularly along lamination planes. Not suitable for microfossil analysis.Notes: Sample collected from a roughly 5-ft-high outcrop with east-west oriented bedding or jointing and boulders along the base of the exposure.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS006 Collected:
07/12/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.18314 W120.80647 (WGS84)Volcanic rock, dark gray, generally aphanitic with very fine euhedral quartz crystals in a dark matrix. Rock is unstratified and unsheared, strong (multiple hammer blows to fracture) with thin (I to 2 mm) quartz veins (no reaction to HC1), and few fractures.
Notes: Sample collected from the south side of a roughly 8-ft-high outcrop.Interpretation:
Diabase within Cretaceous Sandstone (Kv)Sample ID: DS007 Collected:
07/12/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.17736 W120.80093 (WGS84)Sandstone, grayish brown, fine- to coarse-grained, subangular to subrounded, dominantly quartz and lithic grains with minor feldspar (no reaction to HC1). Minor fine lithic gravel up to 6 mm diameter.
Thin (1 cm) beds are defined by grain size variation and textural grading. Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures, no veins, and does not part regularly along lamination planes. Not suitable for microfossil analysis.Notes: Sample collected from one of several low (3-ft-high) exposures, flat and unlayered.
Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS008 Collected:
07/12/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18018 W120.81248 (WGS84)Sandy siltstone, dark grayish brown, visible grains in silty matrix are fine-grained, subangular, quartz or carbonate (very slight reaction to HC1). Stratification defined by thin (I to 2 mm) discontinuous fine-grained sand laminations.
Shoreline Fault Zone Report, Appendix B Geology Page B-76 of 112 Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures and does not part readily along lamination planes. Rare thin (<1 mm) quartz veins. One block is pervasively sheared with abundant quartz veins. Sample is fine-grained and may be suitable for microfossil analysis.Notes: Sample collected from one of several 5-ft-high exposures.
Interpretation:
Fine-grained variant of Cretaceous Sandstone (Ks)Sample ID: DS009 Collected:
07/12/2010 Diver: Craig Porter, Location:
Santa Rosa shelf, N35.18294 W120.81994 (WGS84)Sandstone, light gray, fine- to very fine-grained.
Dominantly subangular quartz and lithic grains with minor feldspar, minor carbonate cement (very slight reaction to HC1). No pumice or other volcaniclastic grains.Laminations are absent and there are no preferred grain orientations to suggest bedding. Rock is strong (multiple hammer blows to fracture) with few fractures and no veins. Not suitable for microfossil analysis.Notes: Sample collected from a roughly 10-ft-high outcrop with a 20-ft-long overhang, very hard to break.Interpretation:
Cretaceous Sandstone (Ks), possibly resistant subunit of Obispo Formation (Tmor)Sample ID: DS010 Collected:
07/12/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18380 W120.82711 (WGS84)Tuff, orange brown, fine- to medium-grained.
Dominantly tuffaceous matrix with trace perlite and pumice clasts (up to 0.5 mm diameter), silicate cement (no reaction to HC1). Laminations are absent, and there are no preferred grain orientations to suggest bedding. Rock is strong (multiple hammer blows to fracture) with few fractures and no veins.Not suitable for microfossil analysis.Notes: Sample collected from a prominent overhanging outcrop with layering oriented roughly east-west.
Interpretation:
Resistant subunit of Obispo Formation (Tmor)Sample ID: DS011 Collected:
07/12/2010 Diver: Craig Porter, Location:
Santa Rosa shelf, N35.18719 W120.82443 (WGS84)Sandstone, medium gray, very fine-grained.
Dominantly subangular quartz and lithic grains with minor feldspar, silicate cement (no reaction to HCI). Weakly expressed laminations are defined by grain size variation.
Rock is strong (multiple hammer blows to fracture) with few fractures and common thin quartz veins. Possibly suitable for microfossil analysis.Notes: Sample collected from one low rise surrounded by sand, kelp bases covered by sand.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS012 Collected:
07/12/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.18969 W120.83016 (WGS84)Volcanic rock, dark gray, aphanitic with very fine euhedral quartz crystals in a dark matrix. Rock is strong (multiple hammer blows to fracture) with abundant very thin quartz veins (no reaction to HCI), and a pervasive shear fabric.Notes: Sample collected from a highly fractured, roughly 10-ft-high outcrop.Interpretation:
Franciscan Complex metavolcanic rock (KJfmv)Shoreline Fault Zone Report, Appendix B Geology Page B-77 of 112 Sample ID: DS013 Collected:
07/12/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.18817 W120.82663 (WGS84)Sandstone, grayish brown, fine- to very fine-grained.
Dominantly subangular quartz and lithic grains with minor feldspar, no reaction to HCI. Prominent laminations are defined by grain sorting. Rock is medium strong (cannot be scraped with knife; fractures with hammer blow) with few fractures and no veins. Possibly suitable for microfossil analysis.Notes: Sample collected from a prominent hog-back ridge.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS014 Collected:
07/12/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18623 W120.82546 (WGS84)Sandstone, grayish brown, fine- to medium-grained, subangular to subrounded, dominantly quartz and lithic grains with minor feldspar (no reaction to HCI). Gravel and coarse-grained sand absent. Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures and no veins. Not suitable for microfossil analysis.Notes: Sample collected from one of several 10-ft-high, upward-tapering pinnacles, unlayered.
Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS015 Collected:
07/12/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18647 W120.82335 (WGS84)Sandstone, grayish brown, fine- to medium-grained, subangular to subrounded, dominantly quartz and lithic grains with minor feldspar (no reaction to HCI). Gravel and coarse-grained sand absent. Rock is medium strong (cannot be scraped with knife, fracture with hammer blow) with few fractures and no veins. Not suitable for microfossil analysis.Notes: Sample collected from an unlayered, 5-ft-high outcrop.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS016 Collected:
07/12/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18263 W120.82531 (WGS84)Tuff, medium gray weathered to'orange brown, very fine-grained.
Dominantly tuffaceous matrix with trace perlite and pumice clasts (up to 0.5 mm diameter), silicate cement (no reaction to HCI). Laminations defined by oxide staining, may indicate textural variation.
Rock is strong (multiple hammer blows to fracture) with few fractures and no veins. Not suitable for microfossil analysis.Notes: Sample collected from a flat surface with deep cracks spaced about 30 ft apart.Interpretation:
Resistant subunit of Obispo Formation (Tmor)Sample ID: DS017 Collected:
07/13/2010, Diver: Carson Porter Shoreline Fault Zone Report, Appendix B Geology Page B-78 of 112 Location:
Santa Rosa shelf, N35.19645 W120.84567 (WGS84)Volcanic rock, dark greenish brown, aphanitic with few visible crystals in a dark matrix. Rock is unstratified, highly sheared, and medium strong (cannot be scraped with knife, fractures with hammer blow) with abundant thin (1 to 2 mm) quartz veins (no reaction to HC1), and common fractures.
Notes: Sample collected from a very tall, unlayered, jagged pinnacle, 10-15 ft wide; base of pinnacle beyond visible range.Interpretation:
Franciscan Complex metavolcanic rock (KJfmv)Sample ID: DS018 Collected:
07/13/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.19796 W120.84905 (WGS84)Sample description:
Volcanic rock, dark greenish gray, aphanitic with few visible crystals in a dark matrix. Rock is unstratified and strong (multiple hammer blows to fracture) with abundant thin (1 to 2 mm) quartz veins (no reaction to HC1). Shears and fractures are common but do not impart a pervasive fabric.Notes: Sample collected from one of several hogback ridges, water very murky.Interpretation:
Franciscan Complex metavolcanic rock (KJfmv)Sample ID: DS019 Collected:
07/13/20 10, Diver: Carson Porter Location:
Santa Rosa shelf N35.19952 W120.84960 (WGS84)Sandstone, medium gray, very fine-grained.
Dominantly subangular quartz and lithic grains with minor feldspar, silicate cement (no reaction to HCI). Weakly expressed laminations are defined by grain size variation.
Rock is strong (multiple hammer blows to fracture) with common fractures and rare thin quartz veins. Possibly suitable for microfossil analysis.Notes: Sample collected roughly 8 ft from the top of a tall, rounded pinnacle.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS020 Collected:
07/13/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.20623 W120.86724 (WGS84)Volcanic rock, dark greenish gray, aphanitic with few visible crystals in a dark matrix. Rock is unstratified and strong (multiple hammer blows to fracture) with abundant thin (I to 2 mm) quartz veins (no reaction to HCI). Shears are common but do not impart a pervasive fabric, and fractures are common.Notes: Sample collected from an unlayered, steep-sided pinnacle with a rounded top.Interpretation:
Franciscan Complex metavolcanic rock (KJfmv)Sample ID: DS021 Collected:
07/13/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.20452 W120.86454 (WGS84)Volcanic rock, dark greenish gray, aphanitic with few visible crystals in a dark matrix. Rock is unstratified and strong (multiple hammer blows to fracture) with abundant thin (1 to 2 mm) quartz veins (no reaction to HCI). Shears are common but do not impart a pervasive fabric, and fractures are common.Notes: Sample collected from a relatively smooth, unlayered, 50 ft tall pinnacle.Shoreline Fault Zone Report, Appendix B Geology Page B-79 of 112 Interpretation:
Franciscan Complex metavolcanic rock (KJfmv)Sample ID: DS022 Collected:
07/13/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.19457 W120.83265 (WGS84)Sandstone, dark gray, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.Gravel and coarse-grained sand absent. Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with common fractures and common thin quartz and very thin calcite veins (moderately strong reaction to HC1). Common shears disrupt any sense of laminations or bedding. Not suitable for microfossil analysis.Notes: Sample collected from a large, rounded, unlayered, outcrop.Interpretation:
Sheared Cretaceous Sandstone (Ks)Sample ID: DS023 Collected:
07/13/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.19526 W120.83474 (WGS84)Sandstone, grayish brown, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.
Gravel and coarse-grained sand absent. Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with common fractures and common thin quartz veins (no reaction to HCl), rare shears. Not suitable for microfossil analysis.Notes: Sample collected from a thickly layered, angled outcrop.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS024 Collected:
07/13/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18413 W120.81735 (WGS84)Sandstone, light grayish brown, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.
Gravel and coarse-grained sand absent. Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with common fractures and common thin quartz veins (no reaction to HCI), rare shears. Not suitable for microfossil analysis.Notes: Sample collected from a flat outcrop with 2-3 feet of relief and cracks oriented roughly NE-SW, 30 ft toward shore from boat.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS025 Collected:
07/13/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18515 W120.81595 (WGS84)Metamorphic rock, greenish gray, medium-grained with moderately well developed foliation.
Crystal composition dominantly quartz and feldspar with trace pyrite and common chlorite staining.
Rock is strong (multiple hammer blows to fracture) with common fractures.
Trace fine (1 to 2 mm) quartz veins and trace calcite veins (weak reaction to HCI).Notes: Sample collected from a 10 ft tall pinnacle with several rounded knobs and rough areas. Sample thoroughly penetrated by boring clams.Interpretation:
Franciscan Complex greenschist metamorphic rock (KJf)Shoreline Fault Zone Report, Appendix B Geology Page B-80 of 112 Sample ID: DS026 Collected:
07/13/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18653 W120.81631 (WGS84)Sandy siltstone, dark grayish brown, visible grains in silty matrix are fine-grained, subangular, quartz or carbonate (very slight reaction to HCI). Stratification defined by faint thin (I to 2 mm) sand laminations.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures and no shears and does not part readily along lamination planes. Sample is fine-grained and may be suitable for microfossil analysis.Notes: Sample collected from a pinnacle with a large crack in it, with knobs but no ridges, unlayered.
Interpretation:
Fine-grained variant of Cretaceous Sandstone (Ks)Sample ID: DS027 Collected:
07/14/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.17552 W120.82388 (WGS84)Sandy siltstone, dark grayish brown, visible grains in silty matrix are fine-grained, subangular, quartz or carbonate (very slight reaction to HCI). Rock is unstratified, medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures and no shears. Sample is fine-grained and may be suitable for microfossil analysis.Notes: Sample collected from a 5 ft tall ridge above a bedrock platform, very little sand.Interpretation:
Fine-grained variant of Cretaceous Sandstone (Ks)Sample ID: DS028 Collected:
07/14/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.17681 W120.82335 (WGS84)Sandy siltstone, light brown, visible grains in silty matrix are fine-grained, subangular, quartz. Matrix is dolomitized (very slight reaction to HCI). Stratification defined by faint thin (I to 2 mm) sand laminations.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures, no veins, and no shears. Sample is fine-grained and may be suitable for microfossil analysis.Notes: Sample collected from a prominent linear ridge on a bedrock platform.Interpretation:
Fine-grained subunit of Obispo Formation (Tmof), or possibly Rincon Shale (Tr)Sample ID: DS029 Collected:
07/14/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.17631 W120.82138 (WGS84)Sandstone, olive brown, fine-grained, subangular, dominantly lithic grains with quartz and minor feldspar.
Gravel and coarse-grained sand absent. Rock is medium strong (cannot be scraped with knife, fractures with hammer blow)with no fractures, shears, or veins (no reaction to HCI), rare shears. Not suitable for microfossil analysis.Notes: Sample collected from a 4 ft tall linear ridge on a bedrock platform.Interpretation:
Cretaceous Sandstone (Ks), or possibly Franciscan Complex greywacke (KJfg)Sample ID: DS030 Collected:
07/14/20 10, Diver. Craig Porter Location:
Santa Rosa shelf, N35.16707 W120.81 110 (WGS84)Sandy siltstone, dark brown, visible grains in silty matrix are fine-grained, subangular, quartz or carbonate (very slight reaction to HC1). Stratification defined by thin (I to 2 mm) discontinuous fine-grained sand laminations.
Rock Shoreline Fault Zone Report, Appendix B Geology Page B-81 of 112 is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures and does not part readily along lamination planes. Sample is fine-grained and may be suitable for microfossil analysis.Notes: Sample collected from one of several low raised ridges trending NW-SE across a larger bedrock platform.Interpretation:
Fine-grained subunit of the Obispo Formation (Tmof) or fine-grained beds within the resistant subunit of the Obispo Formation (Tmor)Sample ID: DS031 Collected:
07/14/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.16839 W120.80853 (WGS84)Sandy siltstone, dark brown, visible grains in silty matrix are fine-grained, subangular quartz with carbonate cement (strong reaction to HC1). Stratification defined by faint very thin (< 1 mm) sand laminations.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures, no veins, and no shears. Sample is fine-grained and may be suitable for microfossil analysis.Notes: Sample collected from 20 ft tall exposure, rounded on top.Interpretation:
Fine-grained subunit of Obispo Formation (Tmof), or possibly Rincon Shale (Tr)Sample ID: DS032 Collected:
07/14/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.17303 W120.80612 (WGS84)Metamorphic rock, greenish gray, medium-grained with weakly developed foliation.
Crystal composition dominantly quartz and feldspar with trace chlorite.
Rock is strong (multiple hammer blows to fracture) with common fractures and pervasive shearing.
Trace fine (I to 2 mm) quartz veins.Notes: Sample collected from a large, amorphous stack with no indication of layering.Interpretation:
Franciscan Complex greenschist metamorphic rock (KJf)Sample ID: DS033 Collected:
07/14/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.17780 W120.80675 (WGS84)Volcanic rock, dark bluish green, aphanitic with few visible crystals in a dark matrix. Rock is strong (multiple hammer blows to fracture), unstratified with common shears, common thin (1 to 2 mm) quartz veins (no reaction to HCI), and common fractures.
Notes: Sample collected from a broad, unlayered rock platform roughly 5 ft high with low relief on top.Interpretation:
Franciscan Complex metavolcanic rock (KJfhnv)Sample ID: DS034 Collected:
07/13/2010, Diver: Carson Porter Location:
Santa Rosa shelf N35.17864 W120.80451 (WGS84)Sandstone, medium gray, fine- to very fine-grained.
Dominantly subangular quartz and lithic grains with minor feldspar, carbonate cement (strong reaction to HCI). Weakly expressed laminations are defined by grain size variation.
Rock is strong (multiple hammer blows to fracture) with common fractures, rare thin quartz veins, and no shearing.
Possibly suitable for microfossil analysis.Notes: Sample collected from a prominent riser on a small bedrock platform, surrounded by boulders.Interpretation:
Cretaceous Sandstone (Ks)Shoreline Fault Zone Report, Appendix B Geology Page B-82 of 112 Sample ID: DS035 Collected:
07/14/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.17845 W120.82071 (WGS84)Metamorphic rock, greenish gray, medium-grained with weakly developed foliation.
Crystal composition dominantly quartz and feldspar with trace chlorite.
Rock is strong (multiple hammer blows to fracture) with common fractures and pervasive shearing.
Trace fine (I to 2 mm) quartz and calcite veins (moderately strong reaction to HC1).Notes: Not available.
Interpretation:
Franciscan Complex greenschist metamorphic rock (KJf)Sample ID: DS036 Collected:
07/15/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.20062 W120.85300 (WGS84)Volcanic rock, dark bluish green, aphanitic with few visible crystals in a dark matrix. Rock is strong (multiple hammer blows to fracture), unstratified with common shears, common thin (1 to 2 mm) quartz veins (no reaction to HC1), and common fractures.
Notes: Sample collected from a large steep-walled pinnacle with a flat top.Interpretation:
Franciscan Complex metavolcanic rock (KJfrnv)Sample ID: DS037 Collected:
07/15/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.19980 W120.84680 (WGS84)Sandstone, grayish brown, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar and carbonate cement (moderately strong reaction to HCI). Gravel and coarse-grained sand absent, faint bedding defined by grain sorting. Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with common fractures, rare shears. Not suitable for microfossil analysis.Notes: Sample collected from one of several 10 ft high hogback ridges, spaced roughly 10 ft apart with boulders between.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS038 Collected:
07/15/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.19777 W120.84507 (WGS84)Claystone, very dark gray, highly sheared. No visible grains, common very thin (< 1 mm) calcite veins (strong reaction to HCI), laminations if present are obscured by shear fabric. Rock is weak (can be scraped with a pocketknife, cannot be scratched with fingernail) with common fractures.
Possibly suitable for microfossil analysis.Notes: Sample collected from a low exposure 30-35 ft across and 6 ft high, surrounded by sand.Interpretation:
Franciscan Complex m6lange Sample ID: DS039 Collected:
07/15/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.19663 W120.83983 (WGS84)Shoreline Fault Zone Report, Appendix B Geology Page B-83 of 112 Sandstone, dark gray, fine- to medium-grained, subangular, dominantly'quartz and lithic grains with minor feldspar.Trace coarse-grained lithics. Weak sense of bedding defined by grain size variation.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with rare fractures and common thin quartz and very thin calcite veins (moderately strong reaction to HCl). Not suitable for microfossil analysis.Notes: Sample collected from one of several low ridges on a bedrock platform.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS040 Collected:
07/15/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.17373 W120.80077 (WGS84)Sandstone, grayish brown, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.
Trace coarse-grained lithics. Weak sense of bedding defined by grain size variation.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with rare fractures and common thin quartz and very thin calcite veins (moderately strong reaction to HCI). Not suitable for microfossil analysis.Notes: Sample collected from a low relief exposure surrounded by boulders.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS041 Collected:
07/15/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.17063 W120.79643 (WGS84)Sandstone, dark gray, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.Gravel and coarse-grained sand absent, no sense of bedding or laminations.
Rock is strong (multiple hammer blows to fracture) with rare fractures and common thin quartz and very thin calcite veins (moderately strong reaction to HC1). Not suitable for microfossil analysis.Notes: Sample collected from a jagged, unlayered pinnacle above a low bedrock platform.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS042 Collected:
07/15/20 10, Diver: Carson Porter Location:
Santa Rosa shelf, N35.16778 W120.79129 (WGS84)Sample description:
Sandstone, dark gray, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.Trace coarse-grained lithics. Weak sense of bedding defined by grain size variation.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with rare fractures and common thin quartz and very thin calcite veins (moderately strong reaction to HCl). Not suitable for microfossil analysis.Notes: Sample collected from a 20 ft long bedrock platform with 3-4 ft wide ridges.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS043 Collected:
07/15/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.18023 W120.80299 (WGS84)Sandstone, dark gray, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.Trace coarse-grained lithics. Weak sense of bedding defined by grain size variation.
Rock is medium strong (cannot Shoreline Fault Zone Report, Appendix B Geology Page B-84 of 112 be scraped with knife, fractures with hammer blow) with rare fractures and common thin quartz and very thin calcite veins (moderately strong reaction to HCI). Not suitable for microfossil analysis.Notes: Sample collected from a long bedrock platform with short ridges.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS044 Collected:
07/15/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18852 W120.83092 (WGS84)Sandy siltstone, dark brown, visible grains in silty matrix are fine-grained, subangular quartz with carbonate cement (strong reaction to HCI). Stratification defined by faint very thin (< 1 mm) sand laminations.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with few fractures, no veins, and no shears. Sample is fine-grained and may be suitable for microfossil analysis.*Notes: Sample collected from 20 ft tall exposure, rounded on top.Interpretation:
Fine-grained variant of Cretaceous Sandstone (Ks) (preferred), Fine-grained subunit of Obispo Formation (Tmof), or possibly Rincon Shale (Tr) (alternatives)
Shoreline Fault Zone Report, Appendix B Geology Page B785 of 112 Sample ID: DS045 Collected:
07/15/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.18864 W120.82881 (WGS84)Sample description:
No sample taken.Notes: No bedrock exposed, feature targeted from bathymetric data is an artificial reef of broken tribars.Interpretation:
Artificial fill (AF)Sample ID: DS046 Collected:
07/17/2010, Diver: Craig Porter Location:
Santa Rosa shelf, N35.14159 W120.75490 (WGS84)Volcanic rock, greenish and reddish brown, aphanitic with few visible crystals in a dark matrix. Rock is highly weathered, medium strong (cannot be scraped with knife, fractures with hammer blow), unstratified with common shears, and abundant fractures.
Notes: Sample collected from a hummocky, low relief exposure with many cracks and fractures.
Interpretation:
Franciscan Complex metavolcanic rock (KJfmv)Sample ID: DS047 Collected:
07/17/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.14303 W120.75242 (WGS84)Metamorphic rock, greenish gray, medium-grained with weakly developed foliation.
Crystal composition dominantly quartz and feldspar with trace chlorite.
Rock is strong (multiple hammer blows to fracture) with common fractures and pervasive shearing.
Trace fine (I to 2 mm) quartz and calcite veins (moderately strong reaction to HCI).Notes: Sample collected from one of several low, rounded exposures surrounded by cobbles and boulders (no sand).Interpretation:
Franciscan Complex greenschist metamorphic rock (KJf)Sample ID: DS048 Collected:
07/17/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.14304 W120.74387 (WGS84)Sandstone, grayish brown, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.
Trace coarse-grained lithics. Weak sense of bedding defined by grain size variation.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with rare fractures and common thin quartz and very thin calcite veins (moderately strong reaction to HCl). Not suitable for microfossil analysis.Notes: Sample collected from one of several hogback ridges, 10-15 ft wide and about 20 ft apart with sand between.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS049 Collected:
07/17/2010, Diver: Carson Porter Location:
Santa Rosa shelf, N35.14619 W120.74639 (WGS84)Shoreline Fault Zone Report, Appendix B Geology Page B-86 of 112 Volcanic rock, greenish and reddish brown, aphanitic with few visible crystals in a dark matrix. Rock is highly weathered, medium strong (cannot be scraped with knife, fractures with hammer blow), unstratified with common shears, and abundant fractures.
Notes: Sample collected from a hummocky, low relief exposure with many cracks and fractures.
Interpretation:
Franciscan Complex metavolcanic rock (KJfmv)Sample ID: DS050 Collected:
07/17/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.16093 W120.74426 (WGS84)Sandstone, grayish brown, fine- to medium-grained, subangular, dominantly quartz and lithic grains with minor feldspar.
Trace coarse-grained lithics. Weak sense of bedding defined by grain size variation.
Rock is medium strong (cannot be scraped with knife, fractures with hammer blow) with rare fractures and common thin quartz and very thin calcite veins (moderately strong reaction to HC1). Not suitable for microfossil analysis.Notes: Sample collected from a long, flat bedrock exposure with low ridges.Interpretation:
Cretaceous Sandstone (Ks)Sample ID: DS051 Collected:
07/17/20 10, Diver: Craig Porter Location:
Santa Rosa shelf, N35.16041 W120.74676 (WGS84)Volcanic rock, greenish gray, aphanitic with no visible crystals.
Rock is strong (multiple hammer blows to fracture), unstratified with common fractures and no shears.Notes: Sample collected from a roughly 7 ft high, rounded, overhanging exposure.Interpretation:
Franciscan Complex metavolcanic rock (KJfmrv)Shoreline Fault Zone Report, Appendix B Geology Page B-87 of 112 
-35.4 N LTSP GSG 016-1B -1990 x4 I DCP 2'N ++/-GSA SP 292, nsont al. .1994 Hall. Morro Bay Sou a Port San Luis -1973 LTSPGSG 16-6-1990-3 ID I GSASP 292, 464 GS.9 016S1G 3V N+120.8'W 6 121&deg;W I LEGEND-"-Study area-LTSP geologic maps (PG&E, 1988, 1989,1990)
---Published geologic maps (Hall, 1973a and 1973b; Hall, 1979; Hanson et al, 1994;Lettis and Hall, 1994; Wiegers, 2009)Base map: Project DEM (2010), ESRI Data & Maps (2009)N Wt 0 2 4 Miles Kilometers 0 4 8 Map projection and scale: NAD 1983, UTM Zone 1ON, 1:300,000 Areas of previous geologic mapping SHORELINE FAULT ZONE STUDY 1 Pacific Gas and Electric Company Figure B-1-1 Shoreline Fault Zone Report, Appendix B Geology Page B-88 of 112 0 0 CO E 0 40 0 0 co San Luis Hill PGELIDAR survc Note: Contours are generally in agreement, but details between contours in DEM allow much better geomorphic/geologic interpretation of features.Contour interval:
20 feet Map scale: 1:10,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000.............
F e e t Meters 0 100 200 Comparison of (a) USGS topography with the (b) new LIDAR topography at San Luis Hill SHOREUNE FAULT ZONE STUDY IjPacific Gas and Electric Company I Figure B-I-2 Shoreline Fault Zone Report, Appendix B Geology Page B-89 of 1] 2 00 NotesBath:Bryaane conto' eos fromgLTSP%
6al A butIare E 0 0-14 ~DCPP y t: Flk A. tPecho Rock Cno 0 Notes: Bathymetric contours generally agree, but are 40 much more detailed in MBES bathymetric data. The texture of the sea floor in the MBES bathymetric image E allows for detailed geomnorphic/geologic interpretation."A Flanks and top of Pecho Rock not surveyed in MBES I data because of navigation hazard.Bb athyme t da The flat area at the top of Pecho Rock in the MBES CO OW A bathymetric image is a wave-cut platform, possibly the MIS 5e sea-level high stand.0 Depth contours in meters (NAVD-88)al Map scale: 1:7,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000 4g' Feet Meters 0 100 200 CO Comparison of (a) LTSP bathymetry with the$ (b) new MBES bathymetry at Pecho Rock SHORELINE FAULT ZONE STUDY_ Pacific Gas and Electric Company Figure B-1-3 Shoreline Fault Zone Report, Appendix B Geology Page B-90 of 112 Shoreline Fault Zone Report, Appendix B Geology Page B-91 of 112 0 C, 0 N 0 Co Notes: The new MBES bathymetric data offshore with the low-tide LIDAR and airphotos onshore allows better interpretation and correlation of geology onshore to offshore.-in a See Plate B-1A for geology legend.Mapscale:
1:12,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000 Feet oMeter2 0 100 200 Comparison of (a) LTSP geology map with the (b) new geologic map near Olson Hill SHORELINE FAULT ZONE STUDY IPacific Gas and Electric Company Figure B-2-2 Shoreline Fault Zone Report, Appendix B Geology Page B-92 of 1 12 Estero Bay Bay/F Bay Los Osos Valley SAND DUNES+IS LAY SHELF E 0 d)N 0 Co Ca 4)C)Q C3J N l San Luis Obispo Bay SANTA ROSA REEF SHELF 0-o0* Point San Luis SAN LUIS SHELF\p++LEGEND-- PG&E Faults database (2010)N Wt 0 2 Kilometers 0 2 4 and scale: NAD 1983, UTM Zone ION, 1:150,000 Marine Terraces Irish Hills Geomorphic regions in the Shoreline fault zone study area Sand Dunes Note: Boundary between the Islay and Santa Rosa Reef shelves is uncertain and not shown. The Hosgri fault generally separates the continental shelf and continental slope.Shoreline Fault Zone Report, Appendix B Geology Page B-93 of 112 0 Shoreline Fault Zone Report, Appendix B Geology Page B-94 of 112 0 S i&#xfd; 1: .4-'I&#xa3;S LEGEND 20m structure contour on top of bedrock-5m structure contour on top of bedrock PG&E Faults database (2010)...-w Lowstand paleo-stream channel, approximately located b, \Luis Hill -Paleo IValley Map scale: 1:100,000 Map projection:
NAD 1983, UTM Zone 10 North 0 2 4 Miles Kilometers 0 2 4 Structure contours on top of bedrock on the Islay and Santa Rosa Reef shelves SHORELINE FAULT ZONE STUDY!'!Pacific Gas and Electric CompanyI Shoreline Fault Zone Report, Appendix B Geology Page B-95 of 112 0 Shoreline Fault Zone Report, Appendix B Geology Page B-96 ofl112 0 c Map location LEGEND Lineament of Central segment (sub-segment C-2) of the Shoreline fault zone Notes: a) The 2009 MBES bathymetric image shows two small pockmarks in the sand sheet that may have been formed by gas or fluid release along the Central segment of the Shoreline fault zone.b) 2010 MBES bathymetric image of the same area shows the loss of the pockmarks and thinning of the sand sheet, with more bedrock exposed along the fault at the sea floor.Map scalel:2,000 Map projection:
NAD 1983, UTM Zone 10 North 0 200 400 Feet Meters 0 50 100 Migration of sand sheet along the Central segment (C-2) of the Shoreline fault zone between the (a) 2009 and (b) 2010 MBES surveys northwest of Olson Hill SHOREUNE FAULT ZONE STUDY IPacific Gas and Electric Company Figure B-3-5 Shoreline Fault Zone Report, Appendix B Geology Page B-97 of 112 0 0..A A 0, DCPP 44 4~1 ul'Xtal Santa R'osa f I Reef Shelf Sa LusShl To04*imrvn fal ii -11 LEGEND Submerged strandlines (Appendix I, this study)Emergent marine terrace strandlines (Hanson et al., 1994)Hosgri fault zone, dashed where approximatf
-.. .... ?- Other faults discussed in text Dashed where approximate, dotted where concealed, and querried where inferred (names indicated)
Discussion of paleostrandlines in Appendix I Sources of traces in project fault compilation are discussed in Appendix B.Basemap is hillshade developed from Project DEM, 2010.Map scale: 1:100,000 Map projection:
NAD 1983, UTM Zone 10 North 0 1 2 Miles 0 1 2 Faults and paleostrandlines in the Shoreline fault zone study area SHORELINE FAULT ZONE STUDY R Pacific Gas and Electric Company Fgure B-3-6 Shoreline Fault Zone Report, Appendix B Geology Page B-98 of 112 0 Shoreline Fault Zone Report, Appendix B Geology Page B-99 of 112 Fils path S:Xt38000113838t13838.OOZpauresl20101112 Ressriviuvena a~ure Bl-04-02.6; Date: 02120420101; User S. BoAtrrt Unit Surflcial Deposits unonofolrmity Squire.Member rW uncontormity L 0 Belleview Cis Member E Gragg Member uncoformity Miguelito Member 0.Edna Member Monterey Formation progressive unfontrmity Obispo Formation unconformitl Rincon Formation VaquerOs Formation Suaon dsormtlntrusalto ed Sandstone Age 01,5 Unit Thickness Description
-0. Ma to Surfidal deposits:
stream alluvium mearie terraces, fluvial terraces, pr tot tLandslides.
beacu Sor, and sawt waves., unilthied.
Squire Member of the Pmao Forrensofon (Tpps): unsttfined white free-550 ft to medium-graired silly sandstone.
pootty lithlfied, fossiffertes horizons, rare pholad-bored cobbles where Squire Member unasrtrormably overties 33to3OMaberent n3c.M Basal fotlact wrth Betevrew Member Is generally S 6505 Belleviow Member of the Pismoe (Tppb): inkatbedded buff to ligrt gray clasone and finegr.gined sandstone, weankdy to moderately well-lithited.
fossiliferrous horioar, dialertaceurs horions, taystaore fractures sphreroidally Basal rernact witht Gragg Membear as geeralley confotrmable.
5 Gregg Member of the Fortmatron (Tppg) uanrwtrtiredwvine to buff-4.2Ma tr ie- to meidrai-gned sandstone, poosry to moderately well lited, rare diatomaceous silltnots, pebbte conglomerate.
and itaumtnous sandstone.
Basal Cotttain wrrt lower rremrbers of tbe Pismo Formation is untcerrtsn-able..co 5'I-Edna Member of the Piasion Foenatian (Trope): thicily bedded to 1450 ft unstraclied gray to brown snot- to coare-grained saodsonea, moderately welt litrfd. aerCommon bitunirous horas. beasao Chan pebble tonglotrer-ate and tuffaceeis sandston hrSouno Grades lateralty into the Miguelito Member to trhe west arid sooth.Migueolto Member of the Pliaro Formatiora (Tmpm): thinly bedded brown siltstone and daystone, mtodetaly wel lithified, rtan to commoa n 2250 ft Intervals of silisesus and doloneiric atstone, opalin and paotelanreoss shnle, and bituminous sandy siltstone.
Basal cont mac with Monterey Formation at PFunt Buchon Is gradual but Is dascrtbed by Hall (1973a; 1973b) as unconformbe elsewhere in San Luis Obispo County..0 10.4 to 10.5 Mo 15.5 to 15.3 Mo Monterey Formation (Team): thinly bedded white, gray, and brown chert, weathers to chalky white. l limtitted with a rornchoidal fracture habit.fractured and abested. Includes intervals of diatomite with Opalne Chert, tuff, aotd tuffaclOes sandstone aotd stotsions, rate to intervals of sicrreous atI d torrtfic silstone, opaline and porcelanesous shale. and biturinous sandy siltstmte.
Basa Contact Wlong the coastlne a very 2000 ft gradual. grading from itrbOerdded fine-raged diatousteous aOtd tuffaceous sandstone of the Obispo Formation into iterpbdded cheat and samdstonelsiltstone.
Obispo Formation (Two): Resistant subuns (Tmor) is crudely bedded to unstrallied, orange-brown to gray fine-grained zeasitoelt tuff, very well Itthifned, chaotic, uratttalifed intervals with basal s tour ao rate Intervals of btock silly sandstone.
Fine-grained subunit (Tmof) as well bedded ight brown to gray sandstone ama sltly sandstone.
Coarsening gradually up-secton.
includlng abundant invervais of dolmittic and Common intervas of diatomaosus otd tuffacesous sandsones; Diabasa subuitn (Troog) is bron aphanftic to ptotrwnttic inttrushe dikes and sis 1350 0t Tuffaceous subunt (Tmot) is grouped with Tnor subunit along the (t000to 2000 i coastline at DCPP brt is mapped by Hall (1973a; 1973b)elsewnber San on map) Luis Obsog County Based Contact with Rincon Formation Is not exposed al"s coastline but is mapped as conformable In the Irish Hills by Hall (1973a). Contact with basement rock along Coastline may be depasitional.
intrusive, or faulted, Rincon Formation (Tflma: thinly bedded dark brown siltalose and splly 500f0 claystona with Instebe of tdkontftc sandstone.
Not exposed aong oasatine but mapped as Conformrable by Hail (1973b).T 0 1as Vaqueros Formation (TOY): tan to gray conglomerate aot sanrdstone NOt e"PosWd aong Coastline but mapped in the Irish Hitls by Halt (1573b)&#xfd;Cretat ous Sandstone (Ks): well bedded brown fire- to coasse-grained sandstone, noderartly to very weit Sshifed. generally qutal grains with>250011 ominorfaldspor and lithtc graims. Also includes yelowiwsh iroon to black fissie stale. and dark brown fire- to mr ngrened. ustrratlired vesrcular basalt and disasa. Abims Franoscan Coarlex tock along faufted Cotracts.ft Franciscan Complex (also serpentine) 0t Franod..in Complex (KlJt): croatic, unstratified assenbiage of varying litrhooges, Incuding frne-grained metareuolaic rocks (with stmng 02000 it(?) magshab resistivity valuas), shewred Ctaystone (mselnge mautt), glaumphane schist, and Cheh. Serpentine is included in Franc-cas Complex, Regiosally, traywacke sandstone iso pstnearient component of the Franciscan Complex but Is not common within the mapped area descried in this report Stratigraphy of the coastline exposures and offshore area adjacent to the Irish Hills SHORELINE FAULT ZONE STUDY Note: Figure modified from Hall (1973b)I Pacific Gas and Electric Comepany~
I un B-4-2 Shoreline Fault Zone Report, Appendix B Geology Page B-100 of 112 0 0 0 Shoreline Fault Zone Report, Appendix B Geology Page B-101 of 112 0 Shoreline Fault Zone Report, Appendix B Geology Page B-102 of 112 a) I i t 1 SPoint Buchon LEGEND io Rok 521 2010 Helicopter Magnetic 1 Survey Enhancement 0 .Tilt angle of RTP_A: 0 is shown in degrees See Appendix D for discussion of magnetic data i aNotes: CThe onshore right-lateral north-south fault north of SvCoeDischarge Cove aligns with a north-south offset of two northwest-trending magnetic highs. The magnetic anomalies are interpreted to be offset by the same north-south fault. The Shoreline fault does not appear to displace the north-south fault laterally within the limits of resolution (estimated to be about 100 meters per "Alternative V" but clearly less than 200 meters per "Alternative 2").See Plate B-1A for geology legend.oI Map scale: 1:20,000 Map projection:
NAD 1983, UTM Zone 10 North 0 1,000 2,000 i F e Fet Meters 0 500 1,000Comparison of (a) the geology with (b) the magnetic-field anomalies in the DCPP area Qsw SHORELINE FAULT ZONE STUDY o I&#xb6; Pacific Gas and Electric Company Igure B-5-1 Shoreline Fault Zone Report, Appendix B Geology Page 13- 103 of 112 Shoreline Fault Zone Report, Appendix B Geology Page B-104 of 112 0 Shoreline Fault Zone Report, Appendix B Geology Page B-105 of 112 0 Shoreline Fault Zone Report, Appendix B Geology Page B-106 of 112 0 1 N40W fault All O So. lOOm M OoM 200,m 250 M 300m 350 m 400 m lOx exaggraion
-WI Map scale: 1:12,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000 Feet* Meters 0 100 200 300 Comparison of (a) MBES bathymetric image with (b) the interpreted geology and (c) paleostrandlines across the N40W fault SHOREUNE FAULT ZONE STUDY-20 n, Son, SRn N40W fault Om 50n OOnM IO.n 200., 250., 300n 35on, 400., lOx exggnratof M Pacific Gas and Eectric CompanyI Fig-e B-5-4 Shoreline Fault Zone Report, Appendix B Geology Page B-107 of 112 0 0 Note: See legend on Plate B-1Afor geology and Plate I-lAfor paleostrandlines A A'Map scale: 1:12,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000 Feet M ,Meters 0 100 200 300 Comparison of (a) MBES bathymetry with (b)interpreted geology and (c) paleostrandlines across the Central Segment (C-I)Shoreline fault zone west of DCPP SHORELNE FAULT ZONE STUDY 20. Central segment Shoreline fault zone (C-1)-27 a iih-o,.0n n-40m n Om M som 100M 150. 200. 250m 300, 350. 400 lox exaggerabon I Pacific Gas and Electric Company10 Figure B-5-5 Shoreline Fault Zone Report, Appendix B Geology Page B-108 of 112 S....Central segment Shoreline fault zone (C-2) V-20-21 shorene angle" 0. 50m 100m 150m 200m 250m 300m 350m 400.Ix exaggention 0 Mo Central segment Shoreline fault zone (C-2)-20,,,R@- 
:-Om, 5,, 1G lO.m 20m-1I~ oInmg, 0. m m 100 M 150 r 200 mn 250m 300m 350 m 400 m 10x exaggeration Map scale: 1:12,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000 FFeet* Meters 0 100 200 300 Comparison of (a) MBES bathymetry with (b)interpreted geology and (c) paleostrandlines across the Central segment (C-2) Shoreline fault zone southwest of DCPP entrance SHORELINE FAULT ZONE STUDY Pacific Gas and Electric Company Figure B-5-6 Shoreline Fault Zone Report, Appendix B Geology Page 13- 109 of 112 0 0 O Qew b) Geology Note: See legend on Plate B-1A for geology and Plate I-1A for paleostrandlines A'20. 1..m I Central Segment Shoreline fault zone (C-2)0m 50m ro 150Im 200m 25m 3DOO t 3500 400m,, 10x exaggeration Map scale: 1:12,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000 Feet.Meters 0 100 200 300 Comparison of (a) MBES bathymetry with (b)interpreted geology and (c) paleostrandlines across the Central segment (C-2)Shoreline fault zone west of Olson Hill--~- B'Central Segment Shoreline fault zone (C-2)SHORELINE FAULT ZONE STUDY 0. 50. 100n, 150. 200. 250m,, 3000,, 350,m 400Dm, I0x exaggeration
!" Pacific Gas and Electric Company FIrgun B-5-7 Shoreline Fault Zone Report, Appendix B Geology Page B-1 10 of 112 0 0 S Map scale: 1:12,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000 I eFeet.Meters 0 100 200 300 A Central segment Shoreline fault zone (C-3)A'-20.-isa shoreline angle -11.0 shOreline 3fl410 40m 0.smorehne angle-11, sh~oreline angle Comparison of (a) MBES bathymetry with (b)Interpreted geology and (c) paleostrandlines across the Central segment (C-3) of the Shoreline fault zone west of Rattlesnake Creek 50., loon, ISO,,, 200 r, 2500,, 300,,, 350, 400,,, 10. exaggeration SHOREUNE FAULT ZONE STUDYPacific Gas and Electric Company Figure B-5-8 Shoreline Fault Zone Report, Appendix B Geology Page B-111 of 112 A A'-26-20 South segment Shoreline fault zone Wave-cul platform 1 Map scale: 1:12,000 Map projection:
NAD 1983, UTM Zone 10 North 0 500 1,000 Feet___ Meters 0 100 200 300 Comparison of (a) MBES bathymetry with (b)interpreted geology and (c) paleostrandlines across the South segment of the Shoreline fault zone south of Point San Luis I--32 f\A -3 1 m shoreline angle (buhied)-34 -shoreline angle-36 SHORELINE FAULT ZONE STUDY 0 100 200 300 400 Soo 600 700 10x exaggeration Distance (m)Pacific Gas and Electric Company Figure B-5-9 Shoreline Fault Zone Report, Appendix B Geology Page B-112 of 112}}