Seafloor character--Offshore of Bodega Head, California

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What does this data set describe?

Title: Seafloor character--Offshore of Bodega Head, California
Abstract:
This part of DS 781 presents the seafloor-character map Offshore of Bodega Head, California (raster data file is included in "SeafloorCharacter_BodegaHead.zip," which is accessible from https://pubs.usgs.gov/ds/781/OffshoreBodegaHead/data_catalog_OffshoreBodegaHead.html. These data accompany the pamphlet and map sheets of Johnson, S.Y., Dartnell, P., Golden, N.E., Hartwell, S.R., Erdey, M.D., Greene, H.G., Cochrane, G.R., Kvitek, R.G., Manson, M.W., Endris, C.A., Dieter, B.E., Watt, J.T., 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 Bodega Head, California: U.S. Geological Survey Open-File Report 2015–1140, pamphlet 39 p., 10 sheets, scale 1:24,000, https://doi.org/10.3133/ofr20151140.
This raster-format seafloor-character map shows four substrate classes offshore of Bodega Head, California. The substrate classes mapped in this area have been further divided into the following California Marine Life Protection Act depth zones and slope classes: Depth Zone 2 (intertidal to 30 m), Depth Zone 3 (30 to 100 m), Slope Class 1 (0 degrees - 5 degrees), and Slope Class 2 (5 degrees - 30 degrees). Depth Zone 1 (intertidal), Depth Zone 4 (100 to 200 m), Depth Zone 5 (greater than 200 m), and Slopes Classes 3-4 (greater than 30 degrees) are not present in the region covered by this block. The map is created using a supervised classification method described by Cochrane (2008).
References Cited:
California Department of Fish and Game, 2008, California Marine Life Protection Act master plan for marine protected areas; Revised draft: California Department of Fish and Game, accessed April 5 2011, at http://www.dfg.ca.gov/mlpa/masterplan.asp.
Cochrane, G.R., 2008, Video-supervised classification of sonar data for mapping seafloor habitat, in Reynolds, J.R., and Greene, H.G., eds., Marine habitat mapping technology for Alaska: Fairbanks, University of Alaska, Alaska Sea Grant College Program, p. 185-194, accessed April 5, 2011, at http://doc.nprb.org/web/research/research%20pubs/615_habitat_mapping_workshop/Individual%20Chapters%20High-Res/Ch13%20Cochrane.pdf.
Sappington, J.M., Longshore, K.M., and Thompson, D.B., 2007, Quantifying landscape ruggedness for animal habitat analysis--A case study using bighorn sheep in the Mojave Desert: Journal of Wildlife Management, v. 71, p. 1419-1426.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=l908NC
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?
    Erdey, Mercedes D., and Cochrane, Guy R., 2014, Seafloor character--Offshore of Bodega Head, 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: -123.17
    East_Bounding_Coordinate: -122.97
    North_Bounding_Coordinate: 38.41
    South_Bounding_Coordinate: 38.25
  3. What does it look like?
    https://pubs.usgs.gov/ds/781/OffshoreBodegaHead/images/SeafloorCharacter_OffshoreBodegaHead.jpg (JPEG)
    Seafloor character types offshore of Bodega Head.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2010
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: GeoTiff
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 8855 x 8865 x 1, type Pixel
    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 2
      Ordinates (y-coordinates) are specified to the nearest 2
      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?
    SeafloorCharacter_OffshoreBodegaHead.tif.vat
    The shapefile attributes include VALUE - code for the seafloor character classes, COUNT - number of pixels, SLOPE - slope classes, DEPTH_ZONE - depth zones, SUBSTRATE - substrate classes, SUBST_DESC - short description of substrate classes, and FULL_DESC - detailed description of substrate classes. The shapefile can be added to any ESRI ArcMap project. (Source: ESRI)
    Rowid
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    VALUE
    This seafloor-character class was produced using video-supervised maximum-likelihood classification of the bathymetry and backscatter (intensity of return) signals from sonar systems. Derivative roughness (rugosity) and backscatter intensity were used as variants in the classification. The resulting four substrate classes (1-4) were divided into the Depth Zones (see Attribute: DEPTH_ZONE) by adding to the original grid value in increments of 10. Depth Zone 2, add 0 to grid value; Depth Zone 3, add 10 to grid value; Depth Zone 4, add 20 to grid value; and Depth Zone 5, add 30 to grid value. The resulting grid was further classified into Slope Classes (see Attribute: SLOPE) by adding to the classified raster values (including depth zones) in increments of 50. Slope Class 1, add 0 to grid value; Slope Class 2, add 50 to grid value; Slope Class 3, add 100 to grid value; and Slope Class 4, add 150 to grid value. (Source: ESRI)
    Range of values
    Minimum:1
    Maximum:63
    Units:Integers 1 - 63 representing seafloor character classes.
    COUNT
    The number of pixels (2m x 2m size grid cell) represented in each seafloor class (see Attribute: VALUE). (Source: ESRI)
    Range of values
    Minimum:4048
    Maximum:1617655
    Units:Integers 4048 - 1617655 pixel count.
    SLOPE
    The slope zones for the final seafloor-character map grid were identified on the basis of the smoothed bathymetry grid. The smoothing was done by applying focal statistics to the original bathymetry grid. The tool uses a moving window and calculates the mean value of the central pixel within a circular neighborhood of 20 m radius along the whole raster map. The resulting raster map represents a smoothed value highlighting overall trends and eliminates local varieties in the terrain (such as higher slopes along rock outcrops). Slope class values are: 1 (flat; 0 degrees to 5 degrees), 2 (sloping; 5 degrees to 30 degrees), 3 (steeply sloping; 30 degrees to 60 degrees), or 4 (vertical; 60 degrees to 90 degrees), or 5 (overhang; greater than 90 degrees). (Source: USGS)
    Range of values
    Minimum:1
    Maximum:2
    Units:Integer value 1 and 2 representing slope classes as described above.
    DEPTH_ZONE
    The depth zones for the final seafloor-character map grid were identified on the basis of the smoothed bathymetry grid. The smoothing was done by applying focal statistics to the original bathymetry grid. The tool uses a moving window and calculates the mean value of the central pixel within a circular neighborhood of 20 m radius along the whole raster map. The resulting raster map represents a smoothed value highlighting overall trends and eliminates local varieties in the terrain (such as varying depths along rock outcrops). Depth Zone values are: Depth Zone 1, intertidal; Depth Zone 2, intertidal to 30 m; Depth Zone 3, 30 to 100 m; Depth Zone 4, 100 to 200 m; and Depth Zone 5, deeper than 200 m (California Department of Fish and Game, 2008). (Source: USGS)
    Range of values
    Minimum:2
    Maximum:3
    Units:Integer values 2-3 representing slope classes as described above.
    SUBSTRATE
    Coded values of the substrate classes. Class 1, Fine- to medium-grained smooth sediment; Class 2, Mixed smooth sediment and rock; Class 3, Rock and boulder, rugose; Class 4, Medium- to coarse- grained sediment (Source: USGS)
    Range of values
    Minimum:1
    Maximum:4
    Units:Integer values 1-4 representing substrate classes as described above.
    SUBST_DESC
    Summary description of the four substrate classes coded by the attribute SUBSTRATE. Class 1, Fine- to medium-grained smooth sediment; Class 2, Mixed smooth sediment and rock; Class 3, Rock and boulder, rugose; Class 4, Medium to coarse grained (Mobile Sed Features) (Source: USGS) Names are in text form, maximum length: 50
    FULL_DESC
    Detailed description of the four substrate classes coded by the attribute SUBSTRATE. Class 1, Low backscatter, low rugosity, typically mud to medium-grained sand, often rippled and/or burrowed; Class 2, Moderate to very high backscatter, low rugosity, typically coarse-grained sand, gravel, cobble and bedrock; Class 3, High backscatter, and high rugosity, typically boulder and rugose bedrock; Class 4, Very high backscatter, low rugosity; typically medium- to coarse-grained, rippled sediment with some shell hash in shallow depressions (Source: USGS) Names are in text form, maximum length: 250

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Mercedes D. Erdey
    • Guy R. Cochrane
  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 Drakes Bay 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 3)
    Dartnell, Peter, and Kvitek, Rikk G., 2014, Bathymetry--Offshore of Bodega Head, California: Data Series DS 781, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    See metadata for bathymetry ("Bathymetry_OffshoreBodegaHead_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 3)
    Other_Citation_Details:
    See metadata for backscatter datasets ("BackscatterA_8101_OffshoreBodegaHead_metadata.txt", "BackscatterB_7125_OffshoreBodegaHead_metadata.txt" and "BackscatterC_Swath_OffshoreBodegaHead.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 backscatter amplitude data (2-meter resolution)
    imagery (source 3 of 3)
    Edwards, Brian, Phillips, Eleyne, Golden, Nadine, Krigsman, Lisa, and Dartnell, Pete, 2014, L908NC_video_observations: Data Series DS 781, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    See metadata for L0908NC video observations ("l908nc_video_observations_metadata.txt") in DS 781 for source data and postprocessing/reprocessing information.
    Type_of_Source_Media: vector digital data
    Source_Contribution:
    seafloor interpretations from underwater video and sediment samples
  2. How were the data generated, processed, and modified?
    Date: Mar-2013 (process 1 of 6)
    The seafloor-character map was produced using video-supervised maximum likelihood classification of the bathymetry and intensity of return from sonar systems. The classification was supervised using signatures defined by hand-drawn polygons located through sediment samples and video-observation ground truthing applying methodology described in Cochrane (2008). The two variants used in this classification were backscatter intensity and derivative rugosity (from bathymetry data). Rugosity measures terrain ruggedness as the variation in three-dimensional orientation of grid cells within a neighborhood. Vector analysis is used to calculate the dispersion of vectors normal (orthogonal) to grid cells within the specified neighborhood. This method effectively captures variability in slope and aspect into a single measure. Ruggedness values in the output raster map can range from 0 (no terrain variation) to 1 (complete terrain variation). The calculation was performed using the Terrain Ruggedness (VRM) tool (for details, see Sappington and others, 2007).
    Classes I, II and III values were delineated using multivariate analysis. Class IV (mobile sedimentary features) values were determined on the basis of visual characteristics using both bathymetry and backscatter (slight depression in the seafloor, very high backscatter return). The resulting map (gridded at 2 m) was cleaned by hand to remove data-collection artifacts (for example trackline nadir). Editing was performed in Photoshop, with which individual pixels were selected and values adjusted to remove noise. Selection occurred without antialiasing, and the resulting grid was identical but for the edited pixels. The four seafloor classes were then colored to indicate which of the five California MLPA depth zones they are located in: Depth Zone 2 (intertidal to 30 m), Depth Zone 3 (30 to 100 m), Depth Zone 4 (100 to 200 m), or Depth Zone 5 (greater than 200 m). These were further subdivided into one of the following slope classes: Slope Class 1 (0 degrees - 5 degrees), Slope Class 2 (5 degrees - 30 degrees), Slope Class 3 (30 degrees - 60 degrees), or Slope Class 4 (60 degrees - 90 degrees). Depth Zone 1 (intertidal), Depth Zone 4-5 (greater than 100 m), and Slopes Classes 3-4 (greater than 30 degrees) are not present in the region covered by this block. Data sources used in this process:
    • bathymetry
    • backscatter
    • imagery
    Date: 05-Oct-2017 (process 2 of 6)
    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 3 of 6)
    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 4 of 6)
    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 5 of 6)
    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: 25-Jul-2022 (process 6 of 6)
    Edited metadata to fix validation errors and to bring it up to FGDC CSDGM current standards based on data release policies for USGS Coastal and Marine Hazards and Resources Program (CMHRP). No data were 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:
    U.S. Geological Survey
    Attn: Susan Cochran
    Geologist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    scochran@usgs.gov
  3. What similar or related data should the user be aware of?
    Johnson, S.Y., Dartnell, P., Golden, N.E., Hartwell, S.R., Erdey, M.D., Greene, H.G., Cochrane, G.R., Kvitek, R.G., Manson, M.W., Endris, C.A., Dieter, B.E., Watt, J.T., Krisgman, L.M., Sliter, R.W., Lowe, E.N., and Chin, J.L., 2015, California State Waters Map Series--Offshore of Bodega Head, California: Open-File Report 2015-1140, 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?
    Pixel resolution 2 m.
  2. How accurate are the geographic locations?
    Positional information reflects the position of the camera and was collected using a still photo camera, WAAS-enabled GSP unit, recording at between 1 to 2 nm. DGPS (WAAS) accuracy for position is less than 3 meters. (From Garmin GPSMAP 76C/76CS Specifications, M01-10108-00, Rev0304, http://www8.garmin.com/specs/GPSMAP76C_76CSspec.pdf).
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Total coverage for the survey area is 100 percent. Survey area is defined by coverage of both the multibeam bathymetry and backscatter datasets.
  5. How consistent are the relationships among the observations, including topology?
    Classification was done on the basis of training samples delineated by interpreter. The classification was performed using mathematical algorithms then hand-edited by the interpreter to remove noise.

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 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/OffshoreBodegaHead/data/SeafloorCharacter_OffshoreBodegaHead.zip) includes the .tif, .tfw, .tif.aux.xml, and .tif.ovr files, as well as FGDC-compliant metadata for the Seafloor Character data layer in the Bodega Head region of California.
  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: 25-Jul-2022
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/BodegaHead/SeafloorCharacter_OffshoreBodegaHead_metadata.faq.html>
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