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

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What does this data set describe?

Title:
Geology and geomorphology--Offshore of Tomales Point Map Area, California
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. These data accompany the pamphlet and map sheets of Johnson, S.Y., Dartnell, P., Golden, N.E., Hartwell, S.R., Greene, H.G., Erdey, M.D., Cochrane, G.R., Watt, J.T., Kvitek, R.G., Manson, M.W., Endris, C.A., Dieter, B.E., Krigsman, L.M., Sliter, R.W., Lowe, E.N., and Chin, J.L. (S.Y. Johnson and S.A. Cochran, eds.), 2015, California State Waters Map Series—Offshore of Tomales Point, California: U.S. Geological Survey Open-File Report 2015–1088, pamphlet 38 p., 10 sheets, scale 1:24,000, https://doi.org/10.3133/ofr20151088.
Marine geology and geomorphology was mapped in the Offshore of Tomales Point map area, California, from approximate Mean High Water (MHW) to the 3-nautical-mile limit of California's State Waters. 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, digital camera and video imagery, and high-resolution seismic-reflection profiles.
Supplemental_Information:
Additional information about the USGS field activity from which some of these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=S1510NC
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Hartwell, S.R., Johnson, S.Y., and Manson, M.W., 2014, Geology and geomorphology--Offshore of Tomales Point Map Area, California: Data Series DS 781, U.S. Geological Survey, Reston, VA.

    Online Links:

    This is part of the following larger work.

    Golden, Nadine E., 2013, California State Waters Map Series Data Catalog: Data Series DS 781, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -123.09
    East_Bounding_Coordinate: -122.89
    North_Bounding_Coordinate: 38.25
    South_Bounding_Coordinate: 38.10
  3. What does it look like?
    https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/images/Geology_OffshoreTomalesPoint.jpg (JPEG)
    Geology in the Offshore of Tomales Point map area.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 2006
    Ending_Date: 2010
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • GT-polygon composed of chains (730)
    2. What coordinate system is used to represent geographic features?
      The map projection used is WGS 1984 UTM Zone 10N.
      Projection parameters:
      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 coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.0001
      Ordinates (y-coordinates) are specified to the nearest 0.0001
      Planar coordinates are specified in Meter
      The horizontal datum used is D WGS 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    Geology_OffshoreTomalesPoint
    Polygons representing geologic / geomorphic map units (Source: This report)
    OBJECTID
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: ESRI) Coordinates defining the features.
    MapUnitAbbrev
    Map Unit abbreviation (Source: This report)
    ValueDefinition
    QsrRough seafloor
    QmsMarine nearshore and shelf deposits
    QmsdMarine shelf scour depressions
    QmscCoarse-grained marine nearshore and shelf deposits
    QmsfFine-grained marine shelf deposits
    QstbSediments of central Tomales Bay
    QswSand at the mouth of Tomales Bay
    QkdtbSubaqueous delta at the mouth of Walker Creek
    QdtbSeafloor depressions in Tomales Bay
    TuSedimentary rocks, undivided
    TlLaird Sandstone
    KgGranitic rocks
    MapUnit
    short description of map unit (Source: This report) text description of map unit
    Shape_Length
    Length of feature in internal units. (Source: ESRI) Positive real numbers that are automatically generated.
    Shape_Area
    Area of feature in internal units squared. (Source: ESRI) Positive real numbers that are automatically generated.
    RuleID
    Representation rule identifier (Source: This report) 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.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • S.R. Hartwell
    • S.Y. Johnson
    • M.W. Manson
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA
    US

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

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 Tomales Point 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.

How was the data set created?

  1. From what previous works were the data drawn?
    bathymetry (source 1 of 5)
    Dartnell, Peter, and Kvitek, Rikk G., 2014, Bathymetry--Offshore of Tomales Point Map Area, California: Data Series DS 781, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    See metadata for bathymetry ("Bathymetry_OffshoreTomalesPoint_metadata.txt") in DS 781 for source data and postprocessing/reprocessing information.
    Type_of_Source_Media: digital file of gridded bathymetry data (ArcInfo GRID)
    Source_Contribution: Gridded bathymetry data (2-meter resolution).
    backscatter (source 2 of 5)
    Dartnell, Peter, Erdey, Mercedes D., and Kvitek, Rikk G., 2014, Backscatter--Offshore of Tomales Point Map Area, California: Data Series DS 781, U.S. Geological Survey, Reston, VA.

    Online Links:

    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.
    Type_of_Source_Media: digital file of gridded amplitude data (ArcInfo GRID)
    Source_Contribution: Gridded amplitude data (2-meter resolution).
    S-15-10-NC (source 3 of 5)
    U.S. Geological Survey (USGS) , Coastal and Marine Geology Program (CMGP), 2013, Seismic-reflection data acquisition data of field activity S-15-10-NC in offshore Pescadero from 08/02/2010 to 08/04/2010: U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG), Menlo Park, CA.

    Online Links:

    Type_of_Source_Media: ASCII lat/long shot point files
    Source_Contribution:
    Digital seismic data used to interpret subsurface geologic structure
    sediment (source 4 of 5)
    Reid, Jane A., Reid, Jamey M., Jenkins, Chris J., Zimmerman, Mark, Williams, S. Jeffress, and Field, Michael E., 2006, usSEABED—Pacific Coast (California, Oregon, Washington) offshore surficial-sediment data release: Data Series DS 182, U.S. Geological Survey, Menlo Park, CA.

    Online Links:

    Type_of_Source_Media: Esri project files, csv files
    Source_Contribution:
    seafloor sediment and rock samples used to interpret seafloor geology
    imagery (source 5 of 5)
    Golden, Nadine E., and Cochran, Guy R., 2013, California Seafloor Mapping Program video and photograph portal: data release DOI:10.5066/F7J1015K, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    Type_of_Source_Media: seafloor video and photographs
    Source_Contribution:
    seafloor video and photographs used to interpret seafloor geology
  2. How were the data generated, processed, and modified?
    Date: 2012 (process 1 of 7)
    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. Data sources used in this process:
    • bathymetry
    • backscatter
    • S-15-10-NC
    • sediment
    • imagery
    Date: 2011 (process 2 of 7)
    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 others (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 http://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.
    Date: 05-Oct-2017 (process 3 of 7)
    Added Distribution_Information section to metadata to facilitate data download. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
    Date: 05-Oct-2017 (process 4 of 7)
    Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
    Date: 26-Apr-2018 (process 5 of 7)
    Added keywords from Coastal and Marine Ecological Classification Standard (CMECS) to metadata. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
    Date: 19-Oct-2020 (process 6 of 7)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 10-Mar-2023 (process 7 of 7)
    Metadata was modified to bring up to current USGS PCMSC standards. USGS Thesaurus and keywords were added, information for accompanying Open-File Report added to Abstract and Cross Reference sections, Point of Contact and Metadata Contact information was updated, and Process Steps were refined. Information about the data available for download and different Network Resource Name links and details were given in the Standard Order Process section. Minor typos were corrected. No data information was changed. The metadata available from a harvester may supersede metadata bundled within a download file. Users are advised to compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    Susan A Cochran
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Geologist
    2885 Mission Street
    Santa Cruz, CA
    USA

    (831) 460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Johnson, Samuel Y., Dartnell, Peter, Golden, Nadine E., Hartwell, Stephen R., Greene, H. Gary, Erdey, Mercedes D., Cochrane, Guy R., Watt, Janet T., Kvitek, Rikk G., Manson, Michael W., Endris, Charles A., Dieter, Bryan E., Krigsman, Lisa M., Sliter, Ray W., Lowe, Eric N., and Chin, John L., 2015, California State Waters Map Series--Offshore of Tomales Point, California: Open-File Report 2015-1088, U.S. Geological Survey, Reston, VA.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    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.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    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.
  5. How consistent are the relationships among the observations, including topology?
    Map elements were visually checked for overshoots, undershoots, duplicate features, 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.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None
Use_Constraints USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey and California State University, Monterey Bay (CSUMB) as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    345 Middlefield Rd
    Menlo Park, CA
    USA

    (650) 329-4309 (voice)
  2. What's the catalog number I need to order this data set? The .zip file (https://pubs.usgs.gov/ds/781/OffshoreTomalesPoint/data/Geology_OffshoreTomalesPoint.zip) includes the .aux, .dbf, .shp, .shx, .sbx, and .sbn files, as well as FGDC-compliant metadata for the Geology data layer of Offshore of Tomales Point, California, map area.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by 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.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 10-Mar-2023
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA
US

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/SeriesReports/DS_DDS/DS_781/TomalesPoint/Geology_OffshoreTomalesPoint_metadata.faq.html>
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