Sediment grain size data, San Pedro shelf, southern California - TEXTURE.SHP

Frequently anticipated questions:

What does this data set describe?

Title:
Sediment grain size data, San Pedro shelf, southern California - TEXTURE.SHP
Abstract:
Texture.shp is a GIS file describing grain size characteristics of sediment samples collected by the U.S. Geological Survey between November 29 and December 10, 2004 during survey E-2-04-SC.
This data set is one of a collection of digital files of a geographic information system (GIS) of spatially referenced data related to the study of seafloor geology and benthic habitats of the San Pedro shelf off southern California.
The San Pedro shelf study area covers approximately 400 sq km offshore of the metropolitan Los Angeles area out to a water depth of about 150 m (492 ft). The seafloor hosts a rich and varied biologic community and is subject to anthropogenic inputs from shipping traffic, sewage outfall systems, commercial fisheries, and recreational use. Between 1998 and 2004, the U.S. Geological Survey (in cooperation with Los Angeles and Orange County Sanitation Districts) mapped the seafloor with sonar technologies, collected video and still photography, and collected sediment samples to develop a characterization of this shelf area.
Supplemental_Information:
Additional information about the field activities from which this data set was derived are available online at 
 <http://walrus.wr.usgs.gov/infobank/e/e204sc/html/e-2-04-sc.meta.html>
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 ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
  1. How should this data set be cited?

    Phillips, Eleyne L. , Parsons, Charlene, and Wong, Florence L. , 2012, Sediment grain size data, San Pedro shelf, southern California - TEXTURE.SHP: U.S. Geological Survey Data Series 552, U.S. Geological Survey, Menlo Park, CA.

    Online Links:

    • <https://pubs.usgs.gov/ds/552/>

    This is part of the following larger work.

    Wong, Florence L. , Edwards, Brian D. , Dartnell, Peter, and Phillips, Eleyne L. , 2012, Seafloor Geology and Benthic Habitats of the San Pedro shelf, southern California: U.S. Geological Survey Digital Series 552, U.S. Geological Survey, Menlo Park, California.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -118.338133
    East_Bounding_Coordinate: -117.949982
    North_Bounding_Coordinate: 33.715607
    South_Bounding_Coordinate: 33.562234

  3. What does it look like?

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

    Calendar_Date: 2004
    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):

      • Entity point (183)

    2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?

    texture
    sediment grain size properties (Source: Folk, 1980)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    seq
    sequence number by station and sample id (Source: this study)

    sequential whole numbers

    SampleID
    sample identification; BG indicates box/grabber sampling device. (Source: This study)

    sample identification

    LONGITUDE
    longitude (Source: standard usage)

    Range of values
    Minimum:-180
    Maximum:180

    LATITUDE
    latitude (Source: standard usage)

    Range of values
    Minimum:-90
    Maximum:90

    GRAVEL
    percent gravel by weight (Source: Folk, 1980)

    Range of values
    Minimum:0
    Maximum:100

    SAND
    percent sand by weight (Source: Folk, 1980)

    Range of values
    Minimum:0
    Maximum:100

    MUD
    percent mud by weight (Source: Folk, 1980)

    Range of values
    Minimum:0
    Maximum:100

    SILT
    percent silt by weight (Source: Folk, 1980)

    Range of values
    Minimum:0
    Maximum:100

    CLAY
    percent clay by weight (Source: Folk, 1980)

    Range of values
    Minimum:0
    Maximum:100

    FOLK_CLASS
    sediment text classification (Source: Folk, 1980)

    classes based on ratios of gravel, sand, silt, clay

    CLASS_SYM
    sediment class symbol (Source: Folk, 1980)

    abbreviations for names of classes based on ratios of gravel, sand, silt, clay

    GV_GT01
    gravel content > 0.1 percent (Source: this study)

    ValueDefinition
    1gravel content > 0.1 percent

    STATION
    sampling station number (Source: this study)

    sample location sequence number

    SUBID
    box grab sample identification (Source: this study)

    box grab (BG) sample number and sampling interval, if present

    TOP_SAMP
    uppermost subsample flag (Source: this study)

    ValueDefinition
    1uppermost subsample, if more than one present

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    U.S. Geological Survey
    Attn: Florence L. Wong
    345 Middlefield Road Mail Stop 999
    Menlo Park, CA 94025
    USA

    650-329-5327 (voice)
    fwong@usgs.gov

Why was the data set created?

These data are intended for science researchers, students, policy makers, and the general public. The data can be used with geographic information systems (GIS) software to display geologic and oceanographic information.

How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 01-Jun-2010 (process 1 of 3)
    Metadata imported.

    Data sources used in this process:

    • d:\TEMP\xmlFE.tmp

    Date: 2006 (process 2 of 3)
    A determination of sample homogeneity and sorting was made by visual inspection. 5-25 gm of wet sample were used - the lesser amount was taken for better sorted samples. To remove organic material, the sample was placed in beakers with 200 ml or more of distilled water and 5-10 ml of 30-35% hydrogen peroxide (H2O2) and soaked overnight or longer if the bubbling of the oxidation reaction was still observed. The sample was then heated to remove excess H2O2. Salts were removed by centrifugation and decanting.
    Samples were wet-sieve into 3 size classes: gravel (>2mm; on a #10 sieve), sand (2mm-0.063 mm; on #230 sieve) and mud (or silt and clay; collected in graduated cylinders). The gravel and sand fractions are dried and weighed. Sand was analyzed in the USGS settling tubes using SedLabHost (USGS Western Coastal and Marine Geology software) to collect and process the settling velocity data.
    The mud is collected in 1000 ml graduated cylinders to which is added 5-10 ml of a 1% calgon (sodium hexametaphosphate (NaPO3)6) solution, topped off to 1000 ml with distilled water, agitated for 2 minutes, and allowed to sit overnight. The mud is agitated with a stirring rod for two minutes. At time 20 seconds after agitation a 20 ml aliquot of the suspension is taken by pipette, 20 cm deep into the graduated cylinder. The 20 ml fraction is dried and weighted. The dry weight of the 20 ml aliquot is multiplied by 50 to for the total weight of the mud in the 1000 ml suspension (20 ml is 1/50th of the 1000 ml suspension).
    Processor: Charlene Parsons
    The weight data from each size fraction were combined and processed using the USGS WCMG software called pcSDSZ.
    Processor: Eleyne Phillips

    Date: 13-Sep-2010 (process 3 of 3)
    Metadata imported.

    Data sources used in this process:

    • d:\TEMP\xml99.tmp

  3. What similar or related data should the user be aware of?

    Folk, Robert L. , 1980, Petrology of Sedimentary Rocks: Hemphill Publishing Co., Austin TX.

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?

    Commonly reported grain size intervals (phi sizes) are not available for this data set due to file corruption.

  5. How consistent are the relationships among the observations, including topology?

    Point features present.

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: None

  1. Who distributes the data set? (Distributor 1 of 1)

    U.S. Geological Survey
    Attn: Florence L. Wong
    345 Middlefield Road Mail Stop 999
    Menlo Park, CA 94025
    USA

    (650) 329-5327 (voice)
    fwong@usgs.gov

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Please recognize the U.S. Geological Survey (USGS) as the source of this information.
    Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data.
    The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials.

  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 13-Sep-2010
Last Reviewed: 2010
Metadata author:
U.S. Geological Survey
Attn: Florence L Wong
345 Middlefield Road Mail Stop 999
Menlo Park, CA 94025
USA

650-329-5327 (voice)
fwong@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.15 on Mon Jul 30 14:52:59 2012