Seafloor character--Offshore of Gaviota Map Area, California

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• 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?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Cochrane, G.R., Hartwell, S.R., and Johnson, S.Y., 2017, Seafloor character--Offshore of Gaviota Map Area, California:.

   Online Links:

   • https://doi.org/10.5066/F7TH8JWJ

   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:

   • https://pubs.usgs.gov/ds/781/
   • https://www.sciencebase.gov/arcgis/rest/services/Catalog/58a34164e4b0c82512869be3/MapServer
   • https://www.sciencebase.gov/arcgis/services/Catalog/58a34164e4b0c82512869be3/MapServer/WMSServer?request=GetCapabilities&service=WMS

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -120.379749
   East_Bounding_Coordinate: -120.185163
   North_Bounding_Coordinate: 34.474633
   South_Bounding_Coordinate: 34.401551
   

3. What does it look like?

   https://www.sciencebase.gov/catalog/file/get/5898ecd9e4b0efcedb70779e?name=SeafloorCharacter_OffshoreGaviota.jpg (JPEG)

   Seafloor character of Offshore of Gaviota map area

4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 2007

   Ending_Date: 2009

   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 3819 x 8846 x 1, type Pixel
   2. What coordinate system is used to represent geographic features?
      The map projection used is NAD 1983 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 2.0
      Ordinates (y-coordinates) are specified to the nearest 2.0
      Planar coordinates are specified in Meter
      The horizontal datum used is NAD 1983.
      The ellipsoid used is GRS80.
      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_2m_OffshoreGaviota.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 five substrate classes (I-V) 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 X 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; and Slope Class 2, add 50 to grid value. (Source: producer defined)

   Range of values
   Minimum:	1
   Maximum:	122
   Units:	Integers 1 - 122 representing seafloor character classes.

   COUNT

   The number of pixels (2 m x 2 m size grid cell) represented in each seafloor class (see Attribute: VALUE). (Source: ESRI)

   Range of values
   Minimum:	3
   Maximum:	10946990
   Units:	Integers 3 - 10946990 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), or 3 (steeply sloping; 30 degrees to 60 degrees), 4 (vertical; 60 degrees to 90 degrees), or 5 (overhang; greater than 90 degrees). In the Offshore of Gaviota map area, only Slope Classes 1 and 2 are present. (Source: USGS)

   Range of values
   Minimum:	1
   Maximum:	2
   Units:	Integer value 1 or 2 representing slope class of 0-30 degrees 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; and 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). In the Offshore of Gaviota map area, only Depth zones 2, 3, and 4 are present (Source: USGS)

   Range of values
   Minimum:	2
   Maximum:	4
   Units:	Integer values 2-4 representing depth zones 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; Class 5, Hard anthropogenic material (Source: USGS)

   Range of values
   Minimum:	1
   Maximum:	5
   Units:	Integer values 1-5 representing substrate classes as described above.

   SUBST_DESC

   Summary description of the five 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 (in scour depressions); Class 5, Rugged anthropogenic material (Source: USGS) Names are in text form, maximum length: 50

   FULL_DESC

   Detailed description of the five 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, with some shell hash in shallow depressions; Class 5, High backscatter, low rugosity; related to development by humans. (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)
   • G.R. Cochrane
   • S.R. Hartwell
   • S.Y. Johnson
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)

   831-427-4748 (FAX)

   pcmsc_data@usgs.gov

Why was the data set created?

These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify local seafloor character.

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., 2017, Bathymetry--Offshore of Gaviota Map Area, California: Data Series DS 781, U.S. Geological Survey, Reston, VA.

   Online Links:

   • http://pubs.usgs.gov/ds/781/

   Other_Citation_Details:

   See metadata for ("Bathymetry_OffshoreGaviota_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).
   

   backscatter (source 2 of 3)

   Dartnell, Peter, and Kvitek, Rikk G., 2017, Backscatter--Offshore of Gaviota Map Area, California: Data Series DS 781, U.S. Geological Survey, Reston, VA.

   Online Links:

   • http://pubs.usgs.gov/ds/781/

   Other_Citation_Details:

   See metadata for ("Backscatter_gaviota_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).
   

   imagery (source 3 of 3)

   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:

   • https://doi.org/10.5066/F7J1015K

   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: 2016 (process 1 of 4)

   The seafloor-character map was produced using video-supervised maximum likelihood classification of the bathymetry and intensity of return (backscatter) 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), available at http://doc.nprb.org/web/research/research%20pubs/615_habitat_mapping_workshop/Individual%20Chapters%20High-Res/Ch13%20Cochrane.pdf.
   The two variants used in this classification were backscatter intensity and derivative rugosity. 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 within ESRI's Benthic Terrain Modeler toolset (available at http://esriurl.com/5754). Data sources used in this process:

   • bathymetry
   • backscatter
   • imagery

   Date: 06-Apr-2018 (process 2 of 4)

   Metadata was modified to add accompanying USGS Open-File Report to the Larger Works section. USGS Thesaurus and keywords were added. Minor typos were corrected. No data information was changed. 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

   Date: 04-Sep-2018 (process 3 of 4)

   Information for accompanying Open-File Report was moved from secondary Larger Works section to Abstract and Cross Reference sections. Point of Contact information was updated. Details about different Network Resource Name links was given in the Access Instructions section. Phone number for Metadata Contact was corrected. No data information was changed. 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

   Date: 19-Oct-2020 (process 4 of 4)

   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

3. What similar or related data should the user be aware of?
   Johnson, Samuel Y., Dartnell, Peter, Cochrane, Guy R., Hartwell, Stephen R., Golden, Nadine E., Kvitek, Rikk G., and Davenport, Clifton W., 2018, California State Waters Map Series--Offshore of Gaviota, California: Open-File Report 2018-1023, U.S. Geological Survey, Reston, VA.

   Online Links:

   • https://doi.org/10.3133/ofr20181023

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?
   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?
   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, 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.

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 - ScienceBase

   Denver Federal Center, Building 810, Mail Stop 302

   Denver, CO
   

   USA

   1-888-275-8747 (voice)

   sciencebase@usgs.gov
2. What's the catalog number I need to order this data set? The .zip file (SeafloorCharacter_OffshoreGaviota.zip) includes the .lyr, .tfw, .tif, .tif_ColorRamp.SLD, .tif.aux.xml, .tif.ovr, .tif.vat.cpg, and .tif.vat.dbf files, as well as FGDC-compliant metadata for the Seafloor character data layer in the Offshore of Gaviota map area, 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?
   • Availability in digital form:

     Data format:

     The .zip file for the TIFF image includes the .lyr, .tfw, .tif, .tif_ColorRamp.SLD, .tif.aux.xml, .tif.ovr, .tif.vat.cpg, and .tif.vat.dbf files, as well as FGDC-compliant metadata for the Backscatter data layer of Offshore Gaviota, California. in format TIFF (version ArcMap (version 10.0, ESRI, 2011)) Raster data layer is registered TIFF image in the UTM Zone 10 coordinate system with datum NAD83. Size: 1.2

     Network links:

     https://www.sciencebase.gov/catalog/file/get/589a3d7ce4b0efcedb71a670?facet=SeafloorCharacter_OffshoreGaviota https://doi.org/10.5066/F7TH8JWJ https://pubs.usgs.gov/ds/781/

   • Cost to order the data: none

5. What hardware or software do I need in order to use the data set?

   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 TIFF. Users should download the ArcGIS Project File, OffshoreGaviotaGIS.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 Gaviota" 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.

Who wrote the metadata?

Dates:

Last modified: 19-Oct-2020

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)

831-427-4748 (FAX)

pcmsc_data@usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)