Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - JPEG Images of Grab Samples

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Frequently-anticipated questions:

What does this data set describe?
    Title:
    Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - JPEG Images of Grab Samples
    Abstract:
    Bear Lake is a tectonic lake that has existed for at least several hundred thousand years. The lake basin is a relatively simple half graben, a spoon-shaped depression tilted toward the main fault on the east side of the lake. The U.S. Geological Survey, in cooperation with researchers from several universities, has been studying the sediments of Bear Lake since 1996. The general purpose of this effort is to reconstruct past limnological conditions and regional climate on a range of timescales, from hundreds of years to hundreds of thousands of years. This research relates to a variety of human concerns, including water usage in the Bear River basin. Past work has included several coring operations, a seismic-reflection survey, sediment-trap deployments, a barge-mounted drilling operation with the GLAD800 drill rig, and a variety of other studies. The objectives of the September, 2002 operations, preliminarily reported here, were (1) to compile a detailed bathymetric map of the lake using swath-mapping techniques, in order to provide baseline data for a variety of applications and studies, and (2) to complete a sidescan-sonar survey of the lake, providing a nearly complete acoustic image of the lake floor. Limited amounts of subbottom acoustic-reflection data (CHIRP) were also collected, along with samples of lake-floor sediments representative of different kinds of backscatter patterns. These surveys followed an earlier subbottom acoustic-reflection survey (1997), using boomer and 3.5 kHz systems (S. M. Colman, unpublished data).

  1. How should this data set be cited?

    U.S. Geological Survey, 2003, Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - JPEG Images of Grab Samples.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -111.5
    East_Bounding_Coordinate: -111.17
    North_Bounding_Coordinate: 42.2
    South_Bounding_Coordinate: 41.08

  3. What does it look like?

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

    Beginning_Date: 15-Sep-2002
    Ending_Date: 16-Sep-2002
    Currentness_Reference: Ground Condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: tabular digital data

  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.

    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 0.000089992. Longitudes are given to the nearest 0.000089992. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is WGS84.
      The ellipsoid used is WGS84.
      The semi-major axis of the ellipsoid used is 6378137.0000000.
      The flattening of the ellipsoid used is 1/298.26.

  7. How does the data set describe geographic features?

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
    c/o Jane F. Denny
    Geologist, Seafloor Mapping Group
    384 Woods Hole Road
    Woods Hole, MA 012543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

    Hours_of_Service: Monday-Friday, 8am-5pm, Eastern Standard Time

Why was the data set created?
Sediment samples were collected in order to ground-truth the sidescan-sonar data. Differing backscatter regimes were selected to sample in order to map their surficial sediment character.

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: 2003 (process 1 of 1)
    The samples were acquired with a Van Veen grab sampler. The position of each location was recorded using Coastal Oceanographics, Inc HYPACK Max. Latitude and Longitude values were converted to eastings and northings using USGS Mapgen PROJ command (UTM Zone 12, WGS84 Ellipsoid). The location file, listing longitude, latitude, eastings, northings, water depth at sample location, time, date and sample id, was then formated as an ArcView table. The table was imported into ArcView. A shapefile was generated from the table. Photographs of the samples were taken in the lab after cruise completion. JPG images of the grab samples were then hotlinked to sample locations within ArcView.

    Person who carried out this activity:

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@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?

    Positions are accurate within +/- 3 meters (recorded WAAS horizontal accuracy).

  2. How accurate are the geographic locations?

    WAAS is assumed to be accurate within 1-2 meters. Standard GPS is assumed accurate within 5-10 meters. All data were recorded using the WAAS (Wide Area Augmentation System) navigation. All WAAS data are referenced to WGS84 datum. All sample locations are assumed to be accurate to +/- 3 meters.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    These data are known to be complete.

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

    These data were all acquired with a Van Veen Grab Sample off of the same platform. These data were collected within two days.

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: The USGS asks to be referenced in any use of these data.

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

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

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

    JPG Images of Grab Samples

  3. What legal disclaimers am I supposed to read?

    Altough this data set and its lineage have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or it's related materials. The act of distribution shall not constitute any such warranty, and no resposibility is assumed by the USGS in the use of these data or related items. Users must assume resposibility for the proper use of this data. This data should not be used at resolutions for which it is not intended. This data has no been reviewed for conformity with U.S. Geological Survey editorial standards, or the North American Strigraphic code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

  4. How can I download or order the data?

Who wrote the metadata?
Dates:
Last modified: 25-Apr-2003
Last Reviewed: 2003

Metadata author:
Jane F. Denny
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA 02543
USA

508-457-2311 (voice)
508-457-2310 (FAX)
jdenny@usgs.gov

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

Generated by mp version 2.7.17 on Wed Jul 02 14:23:55 2003