Identification_Information:
  Citation:
    Citation_Information:
      Originator: Robert P. Kucks
      Publication_Date: 1999
      Title: Thorium Concentration Data Grid
  Description:
    Abstract:
      Aerial gamma-ray surveys measure the gamma-ray flux produced
      by the radioactive decay of the naturally occurring elements
      K-40, U-238, and Th-232 in the top few centimeters of rock or
      soil ( Th-232 defined here). If the gamma-ray system is properly
      calibrated the data can be expressed in terms of the estimated
      concentrations of the radioactive elements.
    Supplemental_Information:
      Digital Data Series DDS-9 (CD-ROM) contains gridded geophysical
      data (potassium concentration data only defined here) images
      generated from the data, software for displaying and analyzing
      the images, software for processing potential-field geophysical
      data, and documentation files that describe the data and
      software.
    Purpose:
      Because uranium, thorium, and potassium concentration data are
      useful in geologic studies and because the NURE data are the only
      nationwide database on the natural radiation environment, the
      U.S. Geological Survey reprocessed the aerial gamma-ray data
      to produce maps showing surface concentrations of potassium,
      uranium, and thorium for the conterminous United States.
  Time_Period_of_Content:
    Time_Period_Information:
      Range_of_Dates/Times:
        Beginning_Date: 1998
        Ending_Date: 1999
    Currentness_Reference: reprocessing for SDD website
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -125
      East_Bounding_Coordinate: -65
      North_Bounding_Coordinate: 49
      South_Bounding_Coordinate: 25
  Access_Constraints: None
  Use_Constraints: None
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Robert P. Kucks
        Contact_Organization: U.S. Geological Survey
      Contact_Address:
        Address_Type: mailing address
        Address:
          Box 25046, MS 964
          Denver Federal Center
        City: Denver
        State_or_Province: CO
        Postal_Code: 80225-0046
        Country: USA
      Contact_Voice_Telephone: (303) 236-1405
      Contact_Electronic_Mail_Address: rkucks@usgs.gov
  Data_Set_Credit:
    The U.S Geological Survey reprocessed the aerial gamma-ray data
    to produce maps showing surface concentrations of potassium,
    uranium, and thorium for the conterminous United States. These
    maps have been released as USGS Open-File Reports. Some of the
    reprocessed data have also been released in profile form.
    
    USGS employees: Duval, Riggle, and Snyder
  Native_Data_Set_Environment:
    At the USGS, these data are stored in several binary gridded data
    formats on UNIX and PC systems.  Data have been distributed in
    GEOSOFT GXF (an ASCII interchange format), Arc/Info export (e00),
    and ER Mapper binary format.
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: none
      Theme_Keyword: thorium, gamma-ray, radiometric
    Place:
      Place_Keyword_Thesaurus: none
      Place_Keyword: United States
Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report:
      During the period 1975-83, the U.S. Department of Energy carried
      out the National Uranium Resource Evaluation (NURE) Program,
      which included aerial gamma-ray surveys of most of the United
      States. Although many of the airborne gamma-ray systems used to
      make these surveys were calibrated, many of the earlier surveys
      were done without calibration and conversion to the concentrations
      of the radioactive elements. Detailed examinations of the digital
      data available on magnetic tape also showed that many of the
      "calibrated" surveys do not match the data from other "calibrated"
      surveys of adjacent areas. For these reasons, the data must be
      corrected to obtain a consistent data base for the conterminous
      United States. If the gamma-ray system is properly calibrated
      the data can be expressed in terms of the estimated concentrations
      of the radioactive elements.
    Quantitative_Attribute_Accuracy_Assessment:
      Attribute_Accuracy_Value: 0.1 ppm eTh
      Attribute_Accuracy_Explanation:
        The thorium concentration data are usually expressed in units
        of parts per million equivalent thorium.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report:
        The accuracy was dependent on the flight specifications and
        tolerances of the Department of Energy during their surveying.
      Quantitative_Horizontal_Positional_Accuracy_Assessment:
        Horizontal_Positional_Accuracy_Value: 100
        Horizontal_Positional_Accuracy_Explanation: Dependent on flight positioning recovery used by NURE project
    Vertical_Positional_Accuracy:
      Vertical_Positional_Accuracy_Report:
        The accuracy was dependent on the flight specifications and
        tolerances of the Department of Energy during their surveying.
      Quantitative_Vertical_Positional_Accuracy_Assessment:
        Vertical_Positional_Accuracy_Value: 100
        Vertical_Positional_Accuracy_Explanation: Dependent on flight positioning recovery used by NURE project

  Lineage:
    Process_Step:
      Process_Description:
        The thorium concentration data grid was extracted from DDS-9
        and reprojected using USGS in-house developed software. In-house
        software was also used to convert from USGS grid format to Arc-Info
        grid format.
      Source_Used_Citation_Abbreviation:
        %T Modern aerial gamma-ray spectrometry and regional potassium map
        of the conterminous United States
        %T International geochemical mapping
        %J Journal of Geochemical Exploration
        %A Duval, Joseph S.
        %A Darnley, Arthur G. (editor)
        %A Garrett, Robert G. (editor)
        %D 1990


        %T Potassium and thorium maps of the conterminous United States
        %J Open-File Report
        %A Duval, Joseph S.
        %A Jones, William J.
        %A Riggle, Frederick R.
        %A Pitkin, James A.
        %D 1990
        %O Report Number: OF 90-0338


        %T Profiles of gamma-ray and magnetic data for aerial surveys
        over parts of the Western United States from longitude 108 to 126
        degrees W. and from latitude 34 to 49 degrees N.
        %J Digital Data Series
        %A Duval, Joseph S.
        %D 1995
        %O Report Number: DDS-0031
      Process_Date: 1999
      Process_Contact:
        Contact_Information:
          Contact_Person_Primary:
            Contact_Person: Robert P. Kucks
            Contact_Organization: U.S. Geological Survey
          Contact_Address:
            Address:
              Box 25046, MS 964
              Denver Federal Center
            City: Denver
            State_or_Province: CO
            Postal_Code: 80225-0046
            Country: USA
            Address_Type: mailing address
          Contact_Electronic_Mail_Address: rkucks@usgs.gov
          Contact_Voice_Telephone: (303)236-1405
  Logical_Consistency_Report: see Attribute_Accuracy_Report
  Completeness_Report: see Attribute_Accuracy_Report
Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Raster
  Raster_Object_Information:
    Raster_Object_Type: Grid cell
    Row_Count: 1427
    Column_Count: 2305
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Planar:
      Map_Projection:
        Albers_Conical_Equal_Area:
          Standard_Parallel: 29.5
          Standard_Parallel: 45.5
          Longitude_of_Central_Meridian: -96.0
          Latitude_of_Projection_Origin: 37.5
          False_Easting: 0.
          False_Northing: 0.
        Map_Projection_Name: Albers Conical Equal Area
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: row and column
        Coordinate_Representation:
          Abscissa_Resolution: 2.0
          Ordinate_Resolution: 2.0
        Planar_Distance_Units: kilometer
    Geodetic_Model:
      Horizontal_Datum_Name: Noth American Datum of 1927
      Ellipsoid_Name: CLARKE1866
      Semi-major_Axis: 6378.20640
      Denominator_of_Flattening_Ratio: 0.99661
Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label:
        gamma-ray flux produced by the radioactive decay of naturally
        occuring elements
      Entity_Type_Definition: expressed in concentrations of radioactive elements
      Entity_Type_Definition_Source: Well established geophysical data quantity
    Attribute:
      Attribute_Label: thorium concentration
      Attribute_Definition: expressed in units of parts per million equivalent thorium (ppm eTh)
      Attribute_Definition_Source:
        %T Modern aerial gamma-ray spectrometry and regional potassium map
        of the conterminous United States
        %T International geochemical mapping
        %J Journal of Geochemical Exploration
        %A Duval, Joseph S.
        %A Darnley, Arthur G. (editor)
        %A Garrett, Robert G. (editor)
        %D 1990
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0.0
          Range_Domain_Maximum: 24.0
          Attribute_Units_of_Measure: ppm eTh
          Attribute_Measurement_Resolution: 0.1
        Unrepresentable_Domain:
          Cells with a value of -0.3402823E+39 represent areas of no data
          in grid.
      Attribute_Value_Accuracy_Information:
        Attribute_Value_Accuracy_Explanation:
          See discussion in Attribute_Accuracy_Report of
          Data_Quality_Information.
        Attribute_Value_Accuracy: 0.1
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Voice_Telephone: (888)ASK-USGS
      Contact_Address:
        Address_Type: mailing address
        Address:
          Box 25286, Building 810
          Denver Federal Center
        City: Denver
        State_or_Province: CO
        Postal_Code: 80225
        Country: USA
      Contact_Organization_Primary:
        Contact_Organization: USGS Map Distribution
  Resource_Description:
    Digital Data Series DDS-9 has the original grid before
    reprojection and format conversion
  Distribution_Liability:
    The USGS has made every effort to verify the veracity of this
    information, but is not liable for any inaccuracies.
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: ARCE
        Format_Specification: Arc-Info grid format
        Format_Information_Content: gridded data
        File_Decompression_Technique: gunzip
        Transfer_Size: 8.9
        Format_Version_Date: 1993
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: anonymous FTP (File Transfer Protocol)
          Access_Instructions:
            anonymous FTP to musette.cr.usgs.gov
            file available as pub/cdrom_DDS-9/ARC_INFO/usath_sdd.e00.gz
          Online_Computer_and_Operating_System: Hewlett Packard K220 UNIX server - HPUX 10.2
        Offline_Option:
          Offline_Media: CD-ROM
          Recording_Format: ISO 9660
          Compatibility_Information:
            The access software used on the disc currently executes only
            under DOS/WINDOWS on IBM or compatible computers.
    Fees:
      FTP and website are no cost
      unknown for CD_ROM, DDS-9 may be out of print
    Ordering_Instructions: contact above address or phone
    Turnaround: unknown
  Technical_Prerequisites:
    see Compatibility_Information

    for CD_ROM DDS-9:
    CD-ROM driver software
    super VGA video system

    for FTP of grid:
    FTP software
  Available_Time_Period:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 1999
Metadata_Reference_Information:
  Metadata_Date: 19990421
  Metadata_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Robert P. Kucks
        Contact_Organization: U.S. Geological Survey
      Contact_Electronic_Mail_Address: rkucks@usgs.gov
      Contact_Address:
        Address_Type: mailing address
        Address:
          Box 25046, MS 964
          Denver Federal Center
        City: Denver
        State_or_Province: CO
        Postal_Code: 80225
        Country: USA
      Contact_Voice_Telephone: (303)236-1405
  Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998