Gamma-ray bulk density measurements of vibracore JRBP2018-VC01B from Searsville Lake, Jasper Ridge Biological Preserve, Stanford, California

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Frequently anticipated questions:

What does this data set describe?

Title:
Gamma-ray bulk density measurements of vibracore JRBP2018-VC01B from Searsville Lake, Jasper Ridge Biological Preserve, Stanford, California
Abstract:
This portion of the data release presents gamma-ray bulk density measurements of vibracore JRBP2018-VC01B collected from Searsville Lake, Jasper Ridge Biological Preserve, Stanford, California in October 2018 (USGS Field Activity 2018-682-FA). The gamma-ray bulk density data are provided in a comma-delimited file (.csv).
Supplemental_Information:
Additional information about the field activities from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-682-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    SeanPaul M. La Selle, Stegner, M. Allison, Nasr, Brandon M., Hadly, Elizabeth A., Barnosky, Anthony D., and Sherrod, Brian, 20230131, Gamma-ray bulk density measurements of vibracore JRBP2018-VC01B from Searsville Lake, Jasper Ridge Biological Preserve, Stanford, California: data release DOI:10.5066/P98CEB1B, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    SeanPaul M. La Selle, Stegner, M. Allison, Nasr, Brandon M., Hadly, Elizabeth A., Barnosky, Anthony D., and Sherrod, Brian, 2023, Computed Tomography (CT) scans, photographs, X-ray Fluorescence (XRF) scans, grain size, and gamma-ray bulk density data of vibracores from Searsville Lake, Jasper Ridge Biological Preserve, Stanford, California: data release DOI:10.5066/P98CEB1B, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.23787
    East_Bounding_Coordinate: -122.23787
    North_Bounding_Coordinate: 37.40684
    South_Bounding_Coordinate: 37.40684
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 29-Oct-2018
    Ending_Date: 29-Oct-2018
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: comma-delimited text
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (946)
    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 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in Decimal Degrees. The horizontal datum used is 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?
    JRBP2018-VC01B-gammadensity.csv
    Comma Separated Value (CSV) file containing data. The first row is a header row. (Source: Producer Defined)
    core_depth_cm
    Depth of a gamma-ray bulk density measurement (value represents the upper edge of a 1 cm interval). Depths are not corrected for core compaction and represent depth below the lakebed. (Source: Producer Defined)
    Range of values
    Minimum:158
    Maximum:1103
    Units:cm
    Resolution:1
    section_number
    Core was segmented into seven, approximately 150 cm or shorter sections in order to fit in scanning equipment. The section number denotes which section of core a gamma density measurement is collected from, starting from the top of the original, unsegmented core. (Source: Producer Defined)
    Range of values
    Minimum:1
    Maximum:7
    section_depth_cm
    The depth within a core section, starting with 0 cm at the top. (Source: Producer Defined)
    Range of values
    Minimum:0
    Maximum:152
    Units:cm
    gamma_density_gcc
    The calculated gamma-ray bulk density in grams per cubic centimeter. (Source: Producer Defined)
    Range of values
    Minimum:0.0556
    Maximum:1.6995

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • SeanPaul M. La Selle
    • M. Allison Stegner
    • Brandon M. Nasr
    • Elizabeth A. Hadly
    • Anthony D. Barnosky
    • Brian Sherrod
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    PCMSC Science Data Coordinator
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

    831-427-474 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

Data were obtained to characterize downcore sediment density. These data are intended for science researchers, students, policy makers, and the general public.

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: 06-Oct-2020 (process 1 of 2)
    Core JRBP2018-VC01B was collected on October 29, 2018. A handheld global satellite navigation system (GNSS) receiver was used to determine the locations of sediment sample. The core was segmented into 150 cm (or shorter) sections in the field. Scans of 7 unsplit core segments were obtained on a Geotek Multisensor Core Logger (MSCL) at 1-centimeter downcore intervals using a Cesium-137 gamma-ray source and gamma detector that measure gamma-ray attenuation through the core. The reference core thickness was 7.37 cm. Data are reported at the top of the sampling intervals. Density measurements were calibrated using an aluminum calibration piece mounted inside a water-filled aluminum core liner with an inside with an inside diameter of 7.37 centimeters. Gamma-ray bulk density calibration parameters were A=-0.0002 and B=-0.0577. Gamma-ray density measurements below 0.1 grams per cubic centimeter or missing data values were the result of poor contact with the core sample or air voids at the logging location. Anomalous values for gamma-ray bulk density were not excluded from the data. Person who carried out this activity:
    SeanPaul La Selle
    U.S. Geological Survey, Pacific Coastal and Marine Science CEnter
    Geologist
    2885 Mission St.
    Santa Cruz, CA

    831-460-7574 (voice)
    slaselle@usgs.gov
    Date: 23-Feb-2023 (process 2 of 2)
    corrected typo in doi number (scochran@usgs.gov)
  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?
    Gamma-ray density measurements below 0.1 grams per cubic centimeter or missing data values were the result of poor contact with the core sample or air voids at the logging location. Anomalous values for gamma-ray bulk density were not excluded from the data. No formal attribute accuracy tests were conducted
  2. How accurate are the geographic locations?
    The locations of samples were determined using a Garmin etrex 30x handheld global satellite navigation system (GNSS) receiver capable of receiving wide area augmentation system (WAAS) signals. The manufacturer reported accuracy for horizontal positions is 3-5 m while receiving WAAS signals.
  3. How accurate are the heights or depths?
    Core location depths and water depths were not associated with a fixed vertical datum at the time of core collection. No formal positional accuracy tests were conducted, nor were they applicable for this dataset.
  4. Where are the gaps in the data? What is missing?
    Gamma-ray density measurements below 0.1 grams per cubic centimeter or missing data values were the result of poor contact with the core sample or air voids at the logging location. Anomalous values for gamma-ray bulk density were not excluded from the data. Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    No formal logical accuracy tests were conducted

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None. Please see 'Distribution Info' for details.
Use_Constraints None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations.
  1. Who distributes the data set? (Distributor 1 of 1)
    GS ScienceBase
    U.S. Geological Survey
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? Gamma-ray bulk density data are available in comma-delimited text file format(JRBP2018-VC01B-gammadensity.csv), including FGDC-compliant metadata.
  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 for other purposes, nor on all computer systems, 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: 23-Feb-2023
Metadata author:
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
2885 Mission Street
Santa Cruz, CA

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/DataReleases/ScienceBase/DR_P98CEB1B/JRBP2018-VC01B-gammadensity-metadata.faq.html>
Generated by mp version 2.9.51 on Tue Feb 28 13:54:02 2023