Geology and geomorphology--Offshore of Point Reyes Map Map Area, California

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: Janet T. Watt
Originator: Michael W. Manson
Originator: H. Gary Greene
Publication_Date: 2014
Title:
Geology and geomorphology--Offshore of Point Reyes Map Map Area, California
Geospatial_Data_Presentation_Form: vector digital data
Larger_Work_Citation:
Citation_Information:
Originator: Janet T. Watt
Originator: Peter Dartnell
Originator: Nadine E. Golden
Originator: H. Gary Greene
Originator: Mercedes D. Erdey
Originator: Guy R. Cochrane
Originator: Samuel Y. Johnson
Originator: Stephen R. Hartwell
Originator: Rikk G. Kvitek
Originator: Michael W. Manson
Originator: Charles A. Endris
Originator: Bryan E. Dieter
Originator: Ray W. Sliter
Originator: Lisa M. Krigsman
Originator: Erik N. Lowe
Originator: John L. Chin
Publication_Date: 2015
Title:
California State Waters Map Series--Offshore of Point Reyes map area, California
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: Open-File Report
Issue_Identification: OFR 2015-1114
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Online_Linkage: <https://pubs.usgs.gov/of/2015/1114/>
Larger_Work_Citation:
Citation_Information:
Originator: Nadine E. Golden
Publication_Date: 2013
Title: California State Waters Map Series Data Catalog
Geospatial_Data_Presentation_Form: database
Series_Information:
Series_Name: Data Series
Issue_Identification: DS 781
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Online_Linkage: <https://pubs.usgs.gov/ds/781/>

Description:
Abstract:
This part of DS 781 presents data for the geologic and geomorphic map of the Offshore of Point Reyes map area, California. The vector data file is included in "Geology_OffshorePointReyes.zip," which is accessible from <https://pubs.usgs.gov/ds/781/OffshorePointReyes/data_catalog_OffshorePointReyes.html>.

Marine geology and geomorphology was mapped in the Offshore of Point Reyes map area from approximate Mean High Water (MHW) to the 3-nautical-mile limit of California’s State Waters. MHW is defined at an elevation of 1.46 m above the North American Vertical Datum of 1988 (NAVD 88) (Weber and others, 2005). Offshore geologic units were delineated on the basis of integrated analyses of adjacent onshore geology with multibeam bathymetry and backscatter imagery, seafloor-sediment and rock samples (Reid and others, 2006), digital camera and video imagery, and high-resolution seismic-reflection profiles.

The onshore bedrock mapping was compiled from Galloway (1977), Clark and Brabb (1997), and Wagner and Gutierrez (2010). Quaternary mapping was compiled from Witter and others (2006) and Wagner and Gutierrez (2010), with unit contacts modified based on analysis of 2012 LiDAR imagery; and additional Quaternary mapping by M.W. Manson.

The morphology and the geology of the Offshore of Point Reyes map area result from the interplay between tectonics, sea-level rise, local sedimentary processes, and oceanography. The Point Reyes Fault Zone runs through the map area and is an offshore curvilinear reverse Fault Zone (Hoskins and Griffiths, 1971; McCulloch, 1987; Heck and others, 1990; Stozek, 2012) that likely connects with the western San Gregorio fault further to the south (Ryan and others, 2008), making it part of the San Andreas Fault System. The Point Reyes Fault Zone is characterized by a 5 to 11 km-wide zone that is associated with two main fault structures, the Point Reyes Fault and the Western Point Reyes Fault (fig. 1).

Tectonic influences impacting shelf morphology and geology are related to local faulting, folding, uplift, and subsidence. Granitic basement rocks are offset about 1.4 km on the Point Reyes thrust fault offshore of the Point Reyes headland (McCulloch, 1987), and this uplift combined with west-side-up offset of the San Andreas Fault (Grove and Niemi, 2005) resulted in uplift of the Point Reyes Peninsula, including the adjacent Bodega and Tomales shelf. The Western Point Reyes Fault is defined by a broad anticlinal structure visible in both industry and high-resolution seismic datasets and exhibits that same sense of vergence as the Point Reyes Fault. The deformation associated with north-side-up motion across the Point Reyes Fault Zone has resulted in a distinct bathymetric gradient across the Point Reyes Fault, with a shallow bedrock platform to the north and east, and a deeper bedrock platform to the south.

Late Pleistocene uplift of marine terraces on the southern Point Reyes Peninsula suggests active deformation west of the San Andreas Fault (Grove and others, 2010) on offshore structures. The Point Reyes Fault and related structures may be responsible for this recent uplift of the Point Reyes Peninsula, however, the distribution and age control of Pleistocene strata in the Offshore of Point Reyes map area is not well constrained and therefore it is difficult to directly link the uplift onshore with the offshore Point Reyes Fault structures. Pervasive stratal thinning within inferred uppermost Pliocene and Pleistocene (post-Purisima) units above the Western Point Reyes Fault anticline suggests Quaternary active shortening above a curvilinear northeast to north-dipping Point Reyes Fault zone. Lack of clear deformation within the uppermost Pleistocene and Holocene unit suggests activity along the Point Reyes Fault zone has diminished or slowed since 21,000 years ago. In this map area the cumulative (post-Miocene) slip-rate on the Point Reyes Fault Zone is poorly constrained, but is estimated to be 0.3 mm/yr based on vertical offset of granitic basement rocks (McCulloch, 1987; Wills and others, 2008).

With the exception of the bathymetric gradient across the Point Reyes Fault, the offshore part of this map area is largely characterized by a relatively flat (<0.8°) bedrock platform. The continental shelf is quite wide in this area, with the shelfbreak located west of the Farallon high , about 35 km offshore. Sea level has risen about 125 to 130 m over about the last 21,000 years (for example, Lambeck and Chappell, 2001; Peltier and Fairbanks, 2005), leading to broadening of the continental shelf, progressive eastward migration of the shoreline and wave-cut platform, and associated transgressive erosion and deposition (for example, Catuneanu, 2006). Land-derived sediment was carried into this dynamic setting, and then subjected to full Pacific Ocean wave energy and strong currents before deposition or offshore transport.

Much of the inner shelf bedrock platform is composed of Tertiary marine sedimentary rocks, which are underlain by Salinian granitic and metamorphic basement rocks, including the Late Cretaceous porphyritic granite (unit Kgg), which outcrops on the seafloor south of the Point Reyes headland. Unit Kgg appears complexly fractured, similar to onshore exposures, with a distinct massive, bulbous texture in multibeam imagery. The Tertiary strata overlying the granite form the core of the Point Reyes syncline (Weaver, 1949) and include the early Eocene Point Reyes Conglomerate (unit Tpr), mid- to late Miocene Monterey Formation (unit Tm), late Miocene Santa Margarita Formation (unit Tsm), late Miocene Santa Cruz Mudstone (unit Tsc), and late Miocene to early Pliocene Purisima Formation (unit Tp). The Point Reyes Conglomerate is exposed on the seafloor adjacent to onshore outcrops on the Point Reyes headland and has a distinct massive texture with some bedding planes visible, but the strata are highly fractured. Based on stratigraphic correlations from seismic reflection data and onshore wells, combined with multibeam imagery, we infer rocks of the early Eocene Point Reyes Conglomerate extend at least 6 km northwest from onshore exposures at Point Reyes headland. The absence of unit Tsc in onshore wells (Clark and Brabb, 1997) suggests these rocks are unlikely to occur within the Tertiary section of this map area, north of the Point Reyes Fault. In this map area, unit Tu represents seafloor outcrops of a middle Miocene to upper Pliocene sequence overlying unit Tpr, that may include units Tm, Tsm, and Tp. Seafloor exposures of unit Tu are characterized by distinct rhythmic bedding where beds are dipping and by a mottled texture where those beds become flat-lying.

Modern nearshore sediments are mostly sand (unit Qms and Qsw) and a mix of sand, gravel, and cobbles (units Qmsc and Qmsd). The more coarse-grained sands and gravels (units Qmsc and Qmsd) are primarily recognized on the basis of bathymetry and high backscatter. The emergent bedrock platform north and west of the Point Reyes headland is heavily scoured, resulting in large areas of unit Qmsc and associated Qmsd. Both Qmsc and Qmsd typically have abrupt landward contacts with bedrock and form irregular to lenticular exposures that are commonly elongate in the shore-normal direction. Contacts between units Qmsc and Qms are typically gradational. Unit Qmsd forms erosional lags in scoured depressions that are bounded by relatively sharp and less commonly diffuse contacts with unit Qms horizontal sand sheets. These depressions are typically a few tens of centimeters deep and range in size from a few 10's of meters to more than 1 km2.

There is an area of high-backscatter, and rough seafloor southeast of the Point Reyes headland that is notable in that it includes several small, irregular "lumps", with as much as 1 m of positive relief above the seafloor (unit Qsr). Unit Qsr occurs in water depths between 50 and 60 meters, with individual lumps randomly distributed to west-trending. This area on seismic-reflection data shows this lumpy material rests on several meters of latest Pleistocene to Holocene sediment and is thus not bedrock outcrop. Rather, it seems likely that this lumpy material is marine debris, possibly derived from one (or more) of the more than 60 shipwrecks offshore of the Point Reyes Peninsula between 1849 and 1940 (National Park Service, 2012). It is also conceivable that this lumpy terrane consists of biological "hardgrounds". Video transect data crossing unit Qsr near the Point Reyes headland was of insufficient quality to distinguish between these above alternatives.

A transition to more fine-grained marine sediments (unit Qmsf) occurs around 50–60 m depth within most of the map area, however, directly south and east of Drakes Estero, backscatter and seafloor sediment samples (Chin and others, 1997) suggest fine-grained sediments extend into water depths as shallow as 30 m. Unit Qmsf is commonly extensively bioturbated and consists primarily of mud and muddy sand. These fine-grained sediments are inferred to have been derived from the Drakes Estero estuary or from the San Francisco Bay to the south, via predominantly northwest flow at the seafloor (Noble and Gelfenbaum, 1990).

References Cited

Catuneanu, O., 2006, Principles of Sequence Stratigraphy: Amsterdam, Elsevier, 375 p. Chin, J.L., Karl, H.A., and Maher, N.M., 1997, Shallow subsurface geology of the continental shelf, Gulf of the Farallones, California, and its relationship to surficial seafloor characteristics: Marine Geology, v. 137, p. 251-269.

Clark, J.C., and Brabb, E.E., 1997, Geology of the Point Reyes National Seashore and vicinity: U.S. Geological Survey Open-File Report 97-456, scale 1:48,000. Galloway, A.J., 1977, Geology of the Point Reyes Peninsula Marin County, California: California Geological Survey Bulletin 202, scale 1:24,000.

Grove, K. and Niemi, T., 2005, Late Quaternary deformation and slip rates in the northern San Andreas fault zone at Olema Valley, Marin County, California: Tectonophysics, v. 401, p. 231-250.

Grove, K., Sklar, L.S., Scherer, A.M., Lee, G., and Davis, J., 2010, Accelerating and spatially-varying crustal uplift and its geomorphic expression, San Andreas Fault zone north of San Francisco, California: Tectonophysics, v. 495, p. 256-268.

Heck, R.G., Edwards, E.B., Kronen, J.D., Jr., and Willingham, C.R., 1990, Petroleum potential of the offshore outer Santa Cruz and Bodega basins, California, in Garrison, R.E., Greene, H.G., Hicks, K.R., Weber, G.E., and Wright, T.L., eds. Geology and tectonics of the central California coastal region, San Francisco to Monterey: Pacific Section, American Association of Petroleum Geologists Bulletin GB67, p. 143-164.

Hoskins E.G., Griffiths, J.R., 1971, Hydrocarbon potential of northern and central California offshore: American Association of Petroleum Geologists Memoir 15, p. 212-228.

Lambeck, K., and Chappell, J., 2001, Sea level change through the last glacial cycle: Science, v. 292, p. 679-686, doi: 10.1126/science.1059549.

McCulloch, D.S., 1987, Regional geology and hydrocarbon potential of offshore Central California, in Scholl, D.W., Grantz, A., and Vedder, J.G., eds., Geology and resource potential of the continental margin of Western North America and adjacent ocean basins Beaufort Sea to Baja California: Circum-Pacific Council for Energy and Mineral Resources Earth Science Series, v. 6, p. 353-401.

National Park Service, 2012, Shipwrecks at Point Reyes, available at: <http://www.nps.gov/pore/historyculture/upload/map_shipwrecks.pdf>

Noble, M.A. and Gelfenbaum, G., 1990, A pilot study of currents and suspended sediment in the Gulf of the Farallones: U.S. Geological Survey Open-File Report 90-476, 30 p.

Peltier, W.R., and Fairbanks, R.G., 2006, Global glacial ice volume and Last Glacial Maximum duration from an extended Barbados sea level record: Quaternary Science Reviews, v. 25, p. 3,322-3,337.

Reid, J.A., Reid, J.M., Jenkins, C.J., Zimmerman, M., Williams, S.J., and Field, M.E., 2006, usSEABED Pacific Coast (California, Oregon, Washington) offshore surficial-sediment data release: U.S. Geological Survey Data Series 182, available at <https://pubs.usgs.gov/ds/2006/182/>.

Ryan, H.F., Parsons, T., and Sliter, R.W., 2008, Vertical tectonic deformation associated with the San Andreas Fault offshore of San Francisco, California: Tectonophysics, v. 475, p. 209-223.

Stozek, B.A., 2012, Geophysical evidence for Quaternary deformation within the offshore San Andreas fault system, northern California: Masters Thesis, San Francisco State University, 141 p.

Wagner, D.L., and Gutierrez, C.I., 2010, Preliminary Geologic Map of the Napa 30’ x 60’ Quadrangle, California: California Geological Survey, scale 1:100,000.

Weber, K.M., List, J.H., and Morgan, K.L., 2005, An operational Mean High Water datum for determination of shoreline position from topographic lidar data: U.S. Geological Survey Open-File Report 2005 1027, accessed April 5, 2011, at <https://pubs.usgs.gov/of/2005/1027/>.

Wills, C.J., Weldon, R.J., II, and Bryant, W.A., 2008, Appendix A California fault parameters for the National Seismic Hazard Maps and Working Group on California Earthquake Probabilities 2007: U.S. Geological Survey Open-File Report 2007 1437A, 48 p., available at <https://pubs.usgs.gov/of/2007/1437/a/>.

Witter, R.C., Knudsen, K.L., Sowers, J.M., Wentworth, C.M., Koehler, R.D., Randolph, C.E., Brooks, S.K., and Gans, K.D., 2006, Maps of Quaternary Deposits and Liquefaction Susceptibility in the Central San Francisco Bay Region, California, U.S. Geological Survey Open-File Report 06-1037, scale 1:24,000.Bulletin of the Seismological Society of America, v. 95, p. 861-877.

Purpose:
To expand geologic mapping to the seafloor within the California's State Waters, to update coastal geologic mapping, and to contribute to a uniform regional geologic database, which can be used geographic information systems. Additionally, to provide a geologic map for the public and geoscience community to aid in assessments and mitigation of geologic hazards in the Point Reyes coastal region and to provide sufficient geologic information for land-use and land-management decisions both onshore and offshore. This information is not intended for navigational purposes.
Supplemental_Information:

Map political location: Marin County, California Compilation scale: 1:24,000 Base maps used are hillshades generated from IfSAR, LiDAR, and multibeam mapping both onshore and offshore.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 2006
Ending_Date: 2010
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: none planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -123.094
East_Bounding_Coordinate: -122.894
North_Bounding_Coordinate: 38.098
South_Bounding_Coordinate: 37.940
Keywords:
Theme:
Theme_Keyword_Thesaurus: Global Change Master Directory (GCMD)
Theme_Keyword: Oceans > Bathymetry/SeafloorTopography > Bathymetry
Theme_Keyword: Oceans > Bathymetry/SeafloorTopography > Seafloor Topography
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificInformation
Theme_Keyword: environment
Theme_Keyword: oceans
Theme_Keyword: imageryBaseMapsEarthCover
Theme_Keyword: Multibeam bathymetry
Theme:
Theme_Keyword_Thesaurus: General
Theme_Keyword: Benthic marine habitat
Theme_Keyword: Seafloor mapping
Theme_Keyword: Offshore geology
Theme_Keyword: GIS
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: Pacific Ocean
Place_Keyword: State of California
Place_Keyword: Point Reyes
Place_Keyword: Drakes Bay
Place_Keyword: Marin County
Place_Keyword: Drakes Estero
Access_Constraints:
If physical samples or materials are available, constraints on their on-site access are described in "WR CMG Sample Distribution Policy" at URL: <http://walrus.wr.usgs.gov/infobank/programs/html/main/sample-dist-policy.html>
Use_Constraints:
This information is not intended for navigational purposes.
Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data.
Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.
This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USGS Pacific Coastal and Marine Science Center
Contact_Person: Stephen Hartwell
Contact_Position: Geologist
Contact_Address:
Address_Type: physical address
Address: 400 Natural Bridges Drive
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060
Country: USA
Contact_Voice_Telephone: (831) 460-7814
Contact_Facsimile_Telephone: (831) 427-4748
Contact_Electronic_Mail_Address: shartwell@usgs.gov

Native_Data_Set_Environment:
Microsoft Windows Server 2008 R2 Version 6.1 (Build 7601) Service Pack 1; ESRI ArcGIS 10.0.0.2414

Browse_Graphic:
Browse_Graphic_File_Name:
<https://pubs.usgs.gov/ds/781/OffshorePointReyes/images/Geology_OffshorePointReyes.jpg>
Browse_Graphic_File_Description: Geology and Geomorphology Offshore of Point Reyes map area.
Browse_Graphic_File_Type: GIF Offshore of Point Reyes map area

Data_Quality_Information:
Logical_Consistency_Report:
Map elements were visually checked for overshoots, undershoots, duplicate features, polygon closure, and other errors by the lead authors and by the GIS technician(s) who created the digital database. Review drafts of the map were reviewed internally by at least two other geologists for consistency with basic geologic principles and general conformity to USGS mapping standards.
Completeness_Report:
Data are complete: no offshore features that could be accurately identified and represented at the compilation scale of 1:24,000 were eliminated or generalized. The smallest area represented is approximately 100 square meters. All geospatial database elements are attributed.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Polygons were primarily mapped by one of the following methods: (1) interpretation of 2-meter-resolution hillshaded bathymetry data from sonar surveys; (2) interpretation of 2-meter-resolution amplitude (backscatter) data from bathymetric sonar surveys; (3) interpretation of 2-meter interpretation of seismic-reflection-profile data.
Map Unit contact locations were interpreted typically at a scale of between 1:1,000 and 1:2,000 using the above base data. Bathymetric sonar data have a horizontal accuracy greater than the resolution of the base data.
Map unit contacts were digitized by heads-up screen digitization of line data on 2-meter-resolution DEMs described above. Horizontal accuracy is estimated to be between 2 and 5 meters depending on how clearly contacts can be resolved.
Most digitized positions on the map are estimated to have better than 5 m horizontal accuracy. There is no elevation data in the database.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator: Peter Dartnell
Originator: Rikk G. Kvitek
Publication_Date: 2014
Title: Bathymetry--Offshore of Point Reyes Map Area, California
Geospatial_Data_Presentation_Form: raster digital data
Series_Information:
Series_Name: Data Series
Issue_Identification: DS 781
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Other_Citation_Details:
See metadata for bathymetry ("Bathymetry_OffshorePointReyes_metadata.txt") in DS 781 for source data and postprocessing/reprocessing information.
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshorePointReyes/metadata/Bathymetry_OffshorePointReyes_metadata.txt>
Type_of_Source_Media: digital file of gridded bathymetry data (ArcInfo GRID)
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 2007
Ending_Date: 2010
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: DS 781
Source_Contribution: Gridded bathymetry data (2-meter resolution).
Source_Information:
Source_Citation:
Citation_Information:
Originator: Peter Dartnell
Originator: Rikk G. Kvitek
Publication_Date: 2014
Title: Bathymetry--Offshore of Point Reyes Map Area, California
Geospatial_Data_Presentation_Form: raster digital data
Series_Information:
Series_Name: Data Series
Issue_Identification: DS 781
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Other_Citation_Details:
See metadata for backscatter ("BackscatterA_8101_OffshorePointReyes_metadata.txt", "BackscatterB_Swath_OffshorePointReyes_metadata.txt", "BackscatterC_7125_OffshorePointReyes_metadata.txt") in DS 781 for amplitude source data and postprocessing/reprocessing information.
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshorePointReyes/metadata/BackscatterA_8101_OffshorePointReyes_metadata.txt>
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshorePointReyes/metadata/BackscatterB_Swath_OffshorePointReyes_metadata.txt>
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshorePointReyes/metadata/BackscatterC_7125_OffshorePointReyes_metadata.txt>
Type_of_Source_Media: digital file of gridded amplitude data (ArcInfo GRID)
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 2007
Ending_Date: 2010
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: DS 781
Source_Contribution: Gridded amplitude data (2-meter resolution).
Source_Information:
Source_Citation:
Citation_Information:
Originator:
U.S. Geological Survey (USGS), Coastal and Marine Geology Program (CMGP)
Publication_Date: 2013
Title:
Subbottom survey data of field activity S-8-09-NC in Stinson Beach to Point Arena (CA) from 09/08/2009 to 09/30/2009
Publication_Information:
Publication_Place: Menlo Park, CA
Publisher:
U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
Online_Linkage: <http://walrus.wr.usgs.gov/infobank/gos/s-8-09-nc.fmeta.xml>
Online_Linkage:
<http://walrus.wr.usgs.gov/infobank/s/s809nc/html/s-8-09-nc.meta.html>
Type_of_Source_Media: ASCII lat/long shot point files
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20090908
Ending_Date: 20090930
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: S-8-09-NC
Source_Contribution:
Digital seismic data used to interpret subsurface geologic structure
Process_Step:
Process_Description:
Map unit polygons were digitized over underlying 2-meter base layers developed from multibeam bathymetry and backscatter data. Derivatives such as slope and curvature were generated from source rasters. Interpreted rasters include amplitude, hillshaded bathymetry (using various illumination angles and vertical exaggeration), slope, and curvature. Curvature was decomposed into profile and plan curvature for analysis purposes.
Process_Date: 2012
Process_Step:
Process_Description:
The mapped area was extended to the shoreline by using digital orthophotos to interpret the region between the inner edge of the multibeam bathymetry and the approximate shoreline. The approximate shoreline was generated at the NAVD88 +1.46 m contour, defined as the operational MHW shoreline by Weber and others (2005). The resulting boundary was transformed to WGS 84 UTM Zone 10 North in ArcGIS 10 using the NAD83 to WGS84 (ITRF00) transformation algorithm. This boundary was then used to extend and trim both onshore and offshore geology in the print and PDF product. The transformed boundary is contained within the WGS84 "contours" feature class and identified as a water boundary in the associated representation rules.
References Cited:
Blake, M.C., Jr., Graymer, R.W., and Jones, D.L., 2000, Geologic map and map database of parts of Marin, San Francisco, Alameda, Contra Costa, and Sonoma counties, California: U.S. Geological Survey Miscellaneous Field Studies Map 2337, scale 1:62,500.
California Geological Survey, 1974, Alquist-Priolo Earthquake Fault Zone Maps of Inverness quadrangle, scale 1:24,000.
Clark, J.C., and Brabb, E.E., 1997, Geology of the Point Reyes National Seashore and vicinity: U.S. Geological Survey Open-File Report 97 456, scale 1:48,000.
Galloway, A.J., 1976, Geology of the Point Reyes Peninsula Marin County, California: California Geological Survey Bulletin 202, scale 1:24,000.
Weber, K.M., List, J.H., and Morgan, K.L., 2005, An operational Mean High Water datum for determination of shoreline position from topographic lidar data: U.S. Geological Survey Open-File Report 2005-1027, available at <https://pubs.usgs.gov/of/2005/1027/>.
Witter, R.C., Knudsen, K.L., Sowers, J.M., Wentworth, C.M., Koehler, R.D., Randolph, C.E., Brooks, S.K., and Gans, K.D., 2006, Maps of Quaternary Deposits and Liquefaction Susceptibility in the Central San Francisco Bay Region, California, U.S. Geological Survey Open-File Report 06 1037, scale 1:24,000.
Process_Date: 2011
Process_Step:
Process_Description:
Faults were mapped onto shot lines based on the latitude and longitude of seismic picks from field activity S-8-09-NC.
Process_Date: 2013
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Vector
Point_and_Vector_Object_Information:
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains
Point_and_Vector_Object_Count: 779
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Map_Projection_Name: WGS 1984 UTM Zone 10N
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.9996
Longitude_of_Central_Meridian: -123.0
Latitude_of_Projection_Origin: 0.0
False_Easting: 500000.0
False_Northing: 0.0
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 0.0001
Ordinate_Resolution: 0.0001
Planar_Distance_Units: Meter
Geodetic_Model:
Horizontal_Datum_Name: D WGS 1984
Ellipsoid_Name: WGS 1984
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257223563
Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: Geology_OffshorePointReyes
Entity_Type_Definition: Polygons representing geologic / geomorphic map units
Entity_Type_Definition_Source: This report
Attribute:
Attribute_Label: FID
Attribute_Definition: Internal feature number.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain:
Sequential unique whole numbers that are automatically generated.
Attribute:
Attribute_Label: Shape
Attribute_Definition: Feature geometry.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Coordinates defining the features.
Attribute:
Attribute_Label: Type
Attribute_Definition: Map Unit abbreviation
Attribute_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qsr
Enumerated_Domain_Value_Definition: Rough seafloor
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qms
Enumerated_Domain_Value_Definition: Marine nearshore and shelf deposits
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qmsd
Enumerated_Domain_Value_Definition: Marine shelf scour depressions
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qmsc
Enumerated_Domain_Value_Definition: Coarse-grained marine nearshore and shelf deposits
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qmsf
Enumerated_Domain_Value_Definition: Fine-grained marine shelf deposits
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qmsw
Enumerated_Domain_Value_Definition: Marine sediment wave deposits
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Tp
Enumerated_Domain_Value_Definition: Purisima Formation
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Tm
Enumerated_Domain_Value_Definition: Monterey Formation
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Tpr
Enumerated_Domain_Value_Definition: Point Reyes Conglomerate
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Tpr?
Enumerated_Domain_Value_Definition: Point Reyes Conglomerate, questionable
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Tu
Enumerated_Domain_Value_Definition: Tertiary sediments, undivided
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Kgg
Enumerated_Domain_Value_Definition: Porphyritic Granodiorite of Point Reyes
Enumerated_Domain_Value_Definition_Source: This report
Attribute:
Attribute_Label: Shape_Area
Attribute_Definition: Area of feature in internal units squared.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Positive real numbers that are automatically generated.
Distribution_Information:

Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing and physical address
Address: 345 Middlefield Rd
City: Menlo Park
State_or_Province: CA
Postal_Code: 94025-3561
Country: USA
Contact_Voice_Telephone: (650) 329-4309

Distribution_Liability:

These databases, identified as geology maps of offshore Point Reyes and Vicinity, California have been approved for release and publication by the U.S. Geological Survey (USGS). Although these databases have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein.
Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
These data are not intended for navigational use.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: SHP
Format_Version_Number: ArcMap (version 10.0, ESRI , 2011)
Format_Specification:
Point, line, and polygon features are in shapefile format and are projected in UTM Zone 10 coordinates, with datum WGS84.
Format_Information_Content:
The .zip file for a shapefile includes the .aux, .dbf, .shp, .shx, .sbx, and .sbn files, as well as the text (.txt) and XML (.shp.xml) versions of the metadata for the Geology data layer of Offshore Point Reyes, California.
File_Decompression_Technique: WinZip
Transfer_Size: 0.2
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
<https://pubs.usgs.gov/ds/781/OffshorePointReyes/data/Geology_OffshorePointReyes.zip>
Network_Resource_Name: <https://pubs.usgs.gov/ds/781/>
Access_Instructions: Data can be downloaded via the World Wide Web (WWW)
Fees: none
Technical_Prerequisites:
The downloadable data file has been compressed with the "zip" command and can be unzipped with Winzip (or other tool) on Windows systems. To utilize these data, the user must have software capable of uncompressing the WinZip file and importing and viewing an Esri ArcMap SHP. Users should download the ArcGIS Project File, OffshorePointReyesGIS.mxd.zip, a compressed (with the "zip" command) version of the ArcMap document (.mxd) that has all the data layers loaded in the table of contents for "Offshore Point Reyes" and has all the data symbolized as on the OFR map sheets. Download and save this ArcGIS project file, including all data layers, to the directory the user has created for this GIS.

Metadata_Reference_Information:

Metadata_Date: 20140923
Metadata_Review_Date: 20150610
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey, Coastal and Marine Geology Program
Contact_Person: Stephen R. Hartwell
Contact_Address:
Address_Type: mailing and physical address
Address: 400 Natural Bridges Drive
City: Santa Cruz
State_or_Province: CA
Postal_Code: 95060-5792
Country: US
Contact_Voice_Telephone: 831-460-7814
Contact_Facsimile_Telephone: 831-427-4748
Contact_Electronic_Mail_Address: shartwell@usgs.gov
Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

Generated by mp version 2.9.16 on Wed Jun 10 15:20:51 2015