Geochemical and mineralogical maps for soils of the conterminous United States

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Frequently anticipated questions:


What does this data set describe?

Title:
Geochemical and mineralogical maps for soils of the conterminous United States
Abstract:
Geochemical and mineralogical maps along with a histogram, boxplot, and empirical cumulative distribution function plot for each element or mineral whose data are provided in DS-801
  1. How might this data set be cited?
    Smith, David B., Cannon, William F., Woodruff, Laurel G., Solano, Federico, and Ellefsen, Karl J., 2014, Geochemical and mineralogical maps for soils of the conterminous United States: Open-File Report 2014-1082, U.S. Geological Survey, Denver, Colorado.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -124.8
    East_Bounding_Coordinate: -66.95
    North_Bounding_Coordinate: 49.383333
    South_Bounding_Coordinate: 24.5
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2014
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
  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 5244 x 3219, type Pixel
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is World Geodetic System 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Map images are given as colorized GeoTIFF files; the accompanying legend information is presented as an image showing the color associated with a range of element or mineral component concentration values.
    Entity_and_Attribute_Detail_Citation: https://pubs.usgs.gov/of/2014/1082/pdf/ofr2014-1082.pdf

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Smith, David B.
    • Cannon, William F.
    • Woodruff, Laurel G.
    • Solano, Federico
    • Ellefsen, Karl J.
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Federico Solano
    MIDWEST REGION
    Physical Science Technician
    Mail Stop 954
    12201 Sunrise Valley Dr
    Reston, VA
    USA

    703-648-6335 (voice)
    703-648-6252 (FAX)
    fsolanoc@usgs.gov

Why was the data set created?

These maps re-express in convenient visual form characteristics of the data presented in USGS DS-801 that may be helpful for general planning purposes in which soil chemistry and mineralogy are pertinent.

Users of these maps should remember the low-density nature of the data set on which they are based. The maps represent data collected at a density of approximately one site per 1,600 sq km, so there is, on average, about 40km between nearby sample sites. Soil geochemistry can vary considerably over that distance, and this variation will not be accurately portrayed by the interpolation procedure we used. This study, like other low-density geochemical surveys, was designed to reveal regional-, national-, and continental-scale geochemical and mineralogical patterns extending over thousands or hundreds of thousands of square kilometers. The resulting data cannot be used to accurately estimate the concentration of a given chemical element at a site between sampled locations, where a sample was not actually measured in the lab.

How was the data set created?

  1. From what previous works were the data drawn?
    ds801 (source 1 of 1)
    Smith, David B., Cannon, William F., Woodruff, Laurel G., Solano, Federico, Kilburn, James E., and Fey, David L., 2013, Geochemical and mineralogical data for soils of the conterminous United States: Data Series 801, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: digital files
    Source_Contribution:
    Chemical element and mineral component concentrations given in DS-801 are contoured and depicted as maps in OFR-2014-1082
  2. How were the data generated, processed, and modified?
    Date: 2013 (process 1 of 1)
    Chemical element and mineral components drawn from the data of DS-801 were interpolated by an inverse distance weighted (IDW) technique using ArcGIS software. The IDW method used here predicts unique concentration values for an array of 444 sq km grid cells covering the conterminous United States (approximately 8 million sq km). Person who carried out this activity:
    Federico Solano
    MIDWEST REGION
    Physical Science Technician
    Mail Stop 954
    12201 Sunrise Valley Dr
    Reston, VA
    USA

    703-648-6335 (voice)
    703-648-6252 (FAX)
    fsolanoc@usgs.gov
    Data sources used in this process:
    • ds801
  3. What similar or related data should the user be aware of?
    Smith, David B., Cannon, William F., Woodruff, Laurel G., Solano, Federico, Kilburn, James E., and Fey, David L., 2013, Geochemical and mineralogical data for soils of the conterminous United States: Data Series 801, 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?
  2. How accurate are the geographic locations?
    The latitude and longitude of each site was determined in the field at the actual place where the sample is collected (not the location initially specified in the sampling plan prior to field work) using GPS units set to WGS84 Datum, entered as decimal degrees to the full accuracy of the unit.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This study analyzed selected chemical elements and mineral components only. Mineral components were not measured in the samples collected in the top 5cm of the soil column.
  5. How consistent are the relationships among the observations, including topology?
    For mineral components and chemical species that are present only in measurable concentrations only at a small number of sites, the map images are composed using point symbols whose size and color reflects the concentration of that component at the sample site on which the symbol is centered. The GeoTIFF images for those data are shown in web mercator, spherical transverse mercator, centered at 0,0. All other mineral component and chemical species concentrations are depicted using contoured color images, and their GeoTIFF images are provided in geographic (not projected) coordinates using the horizontal datum WGS84.

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)
    USGS Information Services
    Box 25286, Denver Federal Center
    Denver, Colorado
    USA

    1-888-ASK-USGS (voice)
    1-303-202-4695 (FAX)
    infoservices@usgs.gov
  2. What's the catalog number I need to order this data set? USGS Open-File Report 2014-1082
  3. What legal disclaimers am I supposed to read?
    This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards (or with the North American Stratigraphic Code). Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 07-Dec-2016
Metadata author:
Schweitzer, Peter, N
Eastern Mineral Resources Team
12201 Sunrise Valley Drive Mail Stop 954
Reston, VA
USA

703-648-6533 (voice)
pschweitzer@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://mrdata.usgs.gov/metadata/ofr-2014-1082.faq.html>
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