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

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: S.R. Hartwell
Originator: S.Y. Johnson
Originator: M.W. Manson
Publication_Date: 2015
Title:
Geology and geomorphology--Offshore of Tomales Point Map Area, California
Geospatial_Data_Presentation_Form: vector digital data

Larger_Work_Citation:
Citation_Information:
Originator: Samuel Y. Johnson
Originator: Peter Dartnell
Originator: Nadine E. Golden
Originator: Stephen R. Hartwell
Originator: H. Gary Greene
Originator: Mercedes D. Erdey
Originator: Guy R. Cochrane
Originator: Janet T. Watt
Originator: Rikk G. Kvitek
Originator: Michael W. Manson
Originator: Charles A. Endris
Originator: Bryan E. Dieter
Originator: Lisa M. Krigsman
Originator: Ray W. Sliter
Originator: Erik N. Lowe
Originator: John L. Chin
Publication_Date: 2015
Title:
California State Waters Map Series--Offshore of Tomales Point map area, California
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: Open-File Report
Issue_Identification: OFR 2015-1088
Publication_Information:
Publication_Place: Reston, VA
Publisher: U.S. Geological Survey
Online_Linkage: <https://dx.doi.org/10.3133/ofr20151088>
Online_Linkage: <https://pubs.usgs.gov/of/2015/1088/>

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 Tomales Point map area, California. The vector data file is included in "Geology_OffshoreTomalesPoint.zip," which is accessible from <https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/data_catalog_OffshoreTomalesPoint.html>.

The morphology and the geology of the offshore part of the Offshore of Tomales Point map area result from the interplay between tectonics, sea-level rise, local sedimentary processes, and oceanography. The map area is cut by the northwest-trending San Andreas Fault, the right-lateral transform boundary between the North American and Pacific tectonic plates. The San Andreas strikes through Tomales Bay, the northern part of a linear valley that extends from Bolinas through Olema Valley to Bodega Bay, separating mainland California from the Point Reyes Peninsula. Onshore investigations indicate that this section of the San Andreas Fault has an estimated slip rate of about 17 to 25 mm/yr (Bryant and Lundberg, 2002; Grove and Niemi, 2005). The devastating Great 1906 California earthquake (M 7.8) is thought to have nucleated on the San Andreas Fault about 50 kilometers south of this map area offshore of San Francisco (e.g., Bolt, 1968; Lomax, 2005), with the rupture extending northward through the Offshore of Tomales Point map area to the south flank of Cape Mendocino (Lawson, 1908; Brown and Wolfe, 1972).

The Point Reyes Peninsula is bounded to the south and west in the offshore by the north- and east-dipping Point Reyes Thrust Fault (McCulloch, 1987; Heck and others, 1990), which lies about 20 km west of Tomales Point. Granitic basement rocks are offset about 1.4 km on this thrust fault offshore of Point Reyes (McCulloch, 1987), and this uplift combined with west-side-up offset on the San Andreas Fault (Grove and Niemi, 2005) resulted in uplift of the Point Reyes Peninsula, including Tomales Point and the adjacent continental shelf. Grove and others (2010) reported uplift rates of as much as 1 mm/yr for the south flank of the Point Reyes Peninsula based on marine terraces, but reported no datable terrace surfaces that could constrain uplift for the flight of 4-5 terraces exposed farther north along Tomales Point.

Because of this Quaternary uplift and relative lack of sediment supply from coastal watersheds, there is extensive rugged, rocky seafloor beneath the continental shelf in the Offshore of Tomales Point map area. Granitic rocks (unit Kg) on the seafloor are mapped on the basis of massive character, roughness, extensive fractures, and high backscatter (see Backscattter A to D--Offshore of Tomales Point, California, DS 781, for more information). Neogene sedimentary rocks (units Tl and Tu) commonly form distinctive "ribs," created by differential seafloor erosion of dipping beds of variable resistance. The more massive offshore outcrops of unit Tu in the southern part of the map area are inferred to represent more uniform lithologies. Slopes on the granitic seafloor (generally 1 to 1.3 degrees) are greater than those over sedimentary rock (generally about 0.5 to 0.6 degrees).

Sediment-covered areas occur in gently sloping (less than about 0.6 degrees) mid-shelf environments west and north of Tomales Point, and at the mouth of Tomales Bay. Sediment supply is local, limited to erosion from local coastal bluffs and dunes, small coastal watersheds, and sediment flux out of the mouth of Tomales Bay. Shelf morphology and evolution largely reflects eustacy; 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.

Given present exposure to high wave energy, modern nearshore to mid-shelf sediments are mostly sand (unit Qms) and a mix of sand, gravel, and cobbles (units Qmsc and Qmsd). These sediments are distributed between rocky outcrops at water depths of as much as 65 m (see below). The more coarse-grained sands and gravels (units Qmsc and Qmsd) are primarily recognized on the basis of bathymetry and high backscatter. Unit Qmsd forms erosional lags in scoured depressions that are bounded by relatively sharp contacts with bedrock or sharp to diffuse contacts with units Qms and Qmsc. These scoured depressions are typically a few tens of centimeters deep and range in size from a few 10's of sq m to more than one sq km.

Similar unit Qmsd scour depressions are common along this stretch of the California coast (see, for example, Cacchione and others, 1984; Hallenbeck and others, 2012) where surficial offshore sandy sediment is relatively thin (thus unable to fill the depressions) due to both lack of sediment supply and to erosion and transport of sediment during large northwest winter swells. Such features have been referred to as rippled-scour depressions (see, for example, Cacchione and others, 1984) or sorted bedforms (see, for example, Goff and others, 2005; Trembanis and Hume, 2011). Although the general areas in which both unit Qmsd scour depressions and surrounding mobile sand sheets occur are not likely to change substantially, the boundaries of the individual Qmsd depressions are likely ephemeral, changing seasonally and during significant storm events.

Unit Qmsf consists primarily of mud and muddy sand and is commonly extensively bioturbated. The location of the inboard contact at water depths of about 65 m is based on meager sediment sampling and photographic data and the inference that if must lie offshore of the outer boundary of coarse-grained units Qmsd and Qmsc. This is notably deeper than the inner contact of unit Qmsf offshore of the nearby Russian River (about 50 m; Klise, 1983) which could may reflect both increased wave energy and significantly decreased supply of muddy sediment.

There are two areas of high-backscatter, rough seafloor at water depths of 65 to 70 m west of northern Tomales Point. These areas are notable in that each includes several small (less than about 20,000 sq m), randomly distributed to northwest-trending, irregular "mounds," with as much as 1 m of positive relief above the seafloor (unit Qsr). Seismic-reflection data (see field activity S-15-10-NC) reveal this lumpy material rests on several meters of latest Pleistoce to Holocene sediment and is thus not bedrock outcrop. Rather, it seems likely that this material is marine debris, possibly derived from one (or more) of the more than 60 shipwrecks that have occurred 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"

Units Qsw, Qstb, Qdtb, and Qsdtb comprise sediments in Tomales Bay. Anima and others (2008) conducted a high-resolution bathymetric survey of Tomales Bay and noted that strong tidal currents at the mouth of the bay had created a large field of sandwaves, dunes, and flats (unit Qsw). Unit Qkdtb is a small subaqueous sandy delta deposited at the mouth of Keys Creek, the largest coastal watershed draining into this northern part of Tomales Bay. Unit Qstb occurs south of units Qsw and Qdtb, and comprises largely flat seafloor underlain by mixed sand and silt. Unit Qdtb consists of depressions within the sedimentary fill of Tomales Bay. These depressions commonly occur directly offshore of coastal promontories, cover as much as 74,000 sq m, and are as deep as 9 m.

Map unit polygons were digitized over underlying 2-meter base layers developed from multibeam bathymetry and backscatter data (see Bathymetry--Offshore of Tomales Point, California and Backscattter A to D--Offshore of Tomales Point, California, DS 781). The bathymetry and backscatter data were collected between 2006 and 2010.

References Cited

Anima, R. A., Chin, J.L., Finlayson, D.P., McGann, M.L., and Wong, F.L., 2008, Interferometric sidescan bathymetry, sediment and foraminiferal analyses; a new look at Tomales Bay, Califorina: U.S. Geological Survey Open-File Report 2008 - 1237, 33 p.

Brown, R.D., Jr., and Wolfe, E.W., 1972, Map showing recently active breaks along the San Andreas Fault between Point Delgada and Bolinas Bay, California: U.S. Geological Survey Miscellaneous Investigations Map I-692, scale 1:24,000.

Bryant, W.A., and Lundberg, M.M., compilers, 2002, Fault number 1b, San Andreas fault zone, North Coast section, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, accessed April 4, 2013 at <http://earthquakes.usgs.gov/hazards/qfaults>.

Cacchione, D.A., Drake, D.E., Grant, W.D., and Tate, G.B., 1984, Rippled scour depressions of the inner continental shelf off central California: Journal of Sedimentary Petrology, v. 54, p. 1,280-1,291.

Grove, K., and Niemi, T.M., 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.

Klise, D.H., 1984, Modern sedimentation on the California continental margin adjacent to the Russian River: M.S. thesis, San Jose State University, 120 p.

Hallenbeck, T.R., Kvitek, R.G., and Lindholm, J., 2012, Rippled scour depressions add ecologically significant heterogeneity to soft-bottom habitats on the continental shelf: Marine Ecology Progress Series, v. 468, p. 119-133.

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.

Lawson, A.C., ed., 1908, The California earthquake of April 18, 1906, Report of the State Earthquake Investigation Commission: Carnegie Institution of Washington Publication 87, v. 1, 1451 p. and atlas.

Lomax, A., 2005, A reanalysis of the hypocentral location and related observations for the Great 1906 California earthquake: Bulletin of the Seismological Society of America, v. 95, p. 861-877.

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 Oceans -- Beaufort Sea to Baja California: Houston, Texas, Circum-Pacific Council for Energy and Mineral Resources, Earth Science Series, v. 6., p. 353-401.

National Park Service, 2012, Shipwrecks at Point Reyes, accessed May 1, 2013 at: <http://www.nps.gov/pore/historyculture/upload/map_shipwrecks.pdf>

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 San Gregorio 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: San Mateo County, California Compilation scale: 1:24,000 Base maps used are hillshades generated from IfSAR, LiDAR, and multibeam mapping both onshore and offshore (see Bathymetry Hillshade--Offshore of Tomales Point, California, DS 781, for more information).
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: -123.09
East_Bounding_Coordinate: -122.89
North_Bounding_Coordinate: 38.25
South_Bounding_Coordinate: 38.10

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:
Theme_Keyword_Thesaurus: General
Theme_Keyword: Seafloor Character
Theme_Keyword: Fisheries
Theme_Keyword: Ecosystem
Theme_Keyword: Multibeam
Theme_Keyword: Geology
Theme_Keyword: Bathymetry
Theme_Keyword: Backscatter
Theme_Keyword: Intensity
Theme_Keyword: Ocean Floor Topography
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: USGS
Theme_Keyword: Pacific Coastal and Marine Science Center
Theme_Keyword: CMGP
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: Pacific Ocean
Place_Keyword: State of California
Place_Keyword: Tomales Bay
Place_Keyword: Tomales Point
Place_Keyword: Marin County

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/OffshoreTomalesPoint/images/Geology_OffshoreTomalesPoint.jpg>
Browse_Graphic_File_Description: Geology offshore Tomales Bay.
Browse_Graphic_File_Type: JPEG

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 bathymetric lidar and sonar surveys (see Bathymetry Hillshade--Offshore of Tomales Point, California, DS 781, for more information); (2) interpretation of 2-meter-resolution amplitude (backscatter) data from bathymetric sonar surveys (see BackscatterA_8101; BackscatterB_7125; BackscatterC_Swath; and BackscatterD_USGS--Offshore of Tomales Point, California, DS 781, for more information); (3) interpretation of 2-meter interpretation of seismic-reflection-profile data (see field activity S-15-10-NC).
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 and LiDAR 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 Tomales Point 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_OffshoreTomalesPoint_metadata.txt") in DS 781 for source data and postprocessing/reprocessing information.
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/metadata/Bathymetry_OffshoreTomalesPoint_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: 2006
Ending_Date: 2009
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: Mercedes D. Erdey
Originator: Rikk G. Kvitek
Publication_Date: 2014
Title: Backscatter--Offshore of Tomales Point 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 datasets ("BackscatterA_8101_OffshoreTomalesPoint_metadata.txt", "BackscatterB_7125_OffshoreTomalesPoint_metadata.txt", "BackscatterC_Swath_OffshoreTomalesPoint_metadata.txt", and "BackscatterD_USGS_OffshoreTomalesPoint_metadata.txt") in DS 781 for amplitude source data and postprocessing/reprocessing information.
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/metadata/BackscatterA_8101_OffshoreTomalesPoint_metadata.txt>
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/metadata/BackscatterB_7125_OffshoreTomalesPoint_metadata.txt>
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/metadata/BackscatterC_Swath_OffshoreTomalesPoint_metadata.txt>
Online_Linkage:
<https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/metadata/BackscatterD_USGS_OffshoreTomalesPoint_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: 2006
Ending_Date: 2007
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:
Seismic-reflection data acquisition data of field activity S-15-10-NC in offshore Pescadero from 08/02/2010 to 08/04/2010
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-15-10-nc.fmeta.xml>
Online_Linkage:
<http://walrus.wr.usgs.gov/infobank/s/s1510nc/html/s-15-10-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: 20100802
Ending_Date: 20100804
Source_Currentness_Reference: ground condition
Source_Citation_Abbreviation: S-15-10-NC
Source_Contribution:
Digital seismic data used to interpret subsurface geologic structure
Process_Step:
Process_Description:
Faults were mapped onto shot lines based on the latitude and longitude of seismic picks from field activity S-15-10-NC.
Process_Date: 2012
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.

Only data for offshore map units are released digitally in this publication. For onshore geology see Clark and Brabb (1997) and Wagner and Gutierrez (2010). Onshore Quaternary mapping was compiled from Wagner and Gutierrez (2010), with unit contacts modified based on analysis of 2012 LiDAR map; and additional unpublished mapping by M.W. Manson. Quaternary unit designations are from Witter and ohters (2006). San Andreas Fault traces are from California Geological Survey (1974).

References Cited:

California Geological Survey, 1974, Alquist-Priolo Earthquake Fault Zone Maps of Annapolis and Plantation quadrangles, scale 1:24,000.

Clark, J.C., and Brabb, E.E., 1997, Geology of Point Reyes National Seashore and Vicnity, California: U.S. Geological Survey Open-File Report 97-456, map scale 1:48,000.

Wagner, D.L., and Gutierrez, C.I., 2010, Preliminary Geologic Map of the Napa 30'x60' 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/>.

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

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: 730

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_OffshoreTomalesPoint
Entity_Type_Definition: Polygons representing geologic / geomorphic map units
Entity_Type_Definition_Source: This report
Attribute:
Attribute_Label: OBJECTID
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: MapUnitAbbrev
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: Qstb
Enumerated_Domain_Value_Definition: Sediments of central Tomales Bay
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qsw
Enumerated_Domain_Value_Definition: Sand at the mouth of Tomales Bay
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qkdtb
Enumerated_Domain_Value_Definition: Subaqueous delta at the mouth of Walker Creek
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Qdtb
Enumerated_Domain_Value_Definition: Seafloor depressions in Tomales Bay
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Tu
Enumerated_Domain_Value_Definition: Sedimentary rocks, undivided
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Tl
Enumerated_Domain_Value_Definition: Laird Sandstone
Enumerated_Domain_Value_Definition_Source: This report
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Kg
Enumerated_Domain_Value_Definition: Granitic rocks
Enumerated_Domain_Value_Definition_Source: This report
Attribute:
Attribute_Label: MapUnit
Attribute_Definition: short description of map unit
Attribute_Definition_Source: This report
Attribute_Domain_Values:
Unrepresentable_Domain: text description of map unit
Attribute:
Attribute_Label: Shape_Length
Attribute_Definition: Length of feature in internal units.
Attribute_Definition_Source: ESRI
Attribute_Domain_Values:
Unrepresentable_Domain: Positive real numbers that are automatically generated.
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.
Attribute:
Attribute_Label: RuleID
Attribute_Definition: Representation rule identifier
Attribute_Definition_Source: This report
Attribute_Domain_Values:
Unrepresentable_Domain:
This field contains the representation rule in the ArcGIS file geodatabase which applies a solid color fill of a specified CMYK value to each polygon. Representation rules have the same name as the map unit abbreviation.
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 the offshore Tomales Point map area, 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 offshore Tomales Point, California.
File_Decompression_Technique: WinZip
Transfer_Size: 15.5
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
<https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/data/Geology_OffshoreTomalesPoint.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, OffshoreTomalesPointGIS.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 Tomales Point" and has all the data symbolized as on the data release 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: 20140327
Metadata_Review_Date: 20150519
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 Tue May 19 13:38:51 2015