Metadata:
  Identification_Information:
    Citation:
      Citation_Information:
        Originator: U.S. Geological Survey
        Originator: National Geophysical Data Center
        Publication_Date: 2001
        Title: Aeromagnetic data for East Georgia, Georgia Survey Part 1 of 2
        Geospatial_Data_Presentation_Form: tabular digital data
        Larger_Work_Citation:
          Citation_Information:
            Originator: U.S. Geological Survey
            Originator: National Geophysical Data Center
            Publication_Date: 2001
            Title:
              Digital flight-line aeromagnetic data sets of the
              Conterminous United States, Hawaii, and Puerto Rico
            Series_Information:
              Series_Name: U.S. Geological Survey Open-File Report
              Issue_Identification: 02-361
            Publication_Information:
              Publication_Place: Denver, CO
              Publisher: U.S. Geological Survey
    Description:
      Abstract:
        Aeromagnetic data were collected along flight lines by instruments in an
        aircraft that recorded magnetic-field values and locations.  This dataset
        presents latitude, longitude, altitude, and magnetic-field values.
      Purpose:
        Aeromagnetic surveys are used for geophysical prospecting.  Some
        variations in magnetic measurements are caused by rocks that
        contain significant amounts of magnetic minerals (magnetite being
        the most common).  These anomalies reflect variations in the
        amount and type of magnetic material and the shape and depth of
        the body of rock.
        Aeromagnetic anomaly maps are important tools in mapping
        surficial and buried igneous rocks.  The features and patterns
        of aeromagnetic anomalies can also be used to delineate details
        of subsurface geology including the locations of buried faults and
        the thickness of surficial sedimentary rocks.
      Supplemental_Information:
        The U.S. Geological Survey has contracted or flown numerous
        airborne surveys over a long period (1950's to present).  Not
        all flight-line data have been released to the public
        because of lack of personnel to reformat data and service the
        requests.  With the improvement in digital communication
        and the ability to store and transmit large data sets, the
        USGS is now able to release the flight-line data in a
        common format.

        A companion CD-ROM/web site has been released containing
        magnetic data that were generated by digitizing analog maps.
        Digital flight-line data used to create the analog maps are
        unavailable.  Reference is in the Cross-Reference section of
        this metadata file.
    Time_Period_of_Content:
      Time_Period_Information:
        Range_of_Dates/Times:
          Beginning_Date: 197412
          Ending_Date: 197502
      Currentness_Reference:
        Time period indicates dates of airborne survey
        data collection.  Time period is expressed in the
        format YYYYMM or YYYYMMDD when further accuracy is available.
    Status:
      Progress: complete
      Maintenance_and_Update_Frequency: none planned
    Spatial_Domain:
      Bounding_Coordinates:
        West_Bounding_Coordinate: -83.23
        East_Bounding_Coordinate: -81.12
        North_Bounding_Coordinate: 33.30
        South_Bounding_Coordinate: 31.16
      Data_Set_G-Polygon:
        Data_Set_G-Polygon_Outer_G-Ring:
          G-Ring:
            -82.83 33.33, -81.13 31.63, -81.36 31.15,
            -83.23 33.02, -82.83 33.33
    Keywords:
      Theme:
        Theme_Keyword_Thesaurus: none
        Theme_Keyword: geophysical surveys
        Theme_Keyword: aeromagnetic data
        Theme_Keyword: airborne surveys
        Theme_Keyword: magnetic surveys
        Theme_Keyword: residual magnetic field
        Theme_Keyword: total field
        Theme_Keyword: magnetic
      Theme:
        Theme_Keyword_Thesaurus: ISO 19115 Topic Categories
        Theme_Keyword: geoscientificInformation
      Place:
        Place_Keyword_Thesaurus: none
        Place_Keyword: United States
        Place_Keyword: Georgia
        Place_Keyword: GA
        Place_Keyword: East Georgia
      Place:
        Place_Keyword_Thesaurus: Augmented FIPS 10-4 and FIPS 6-4, version 1.0
        Place_Keyword: 13009 = Baldwin
        Place_Keyword: 13029 = Bryan
        Place_Keyword: 13031 = Bulloch
        Place_Keyword: 13043 = Candler
        Place_Keyword: 13107 = Emanuel
        Place_Keyword: 13109 = Evans
        Place_Keyword: 13125 = Glascock
        Place_Keyword: 13127 = Glynn
        Place_Keyword: 13141 = Hancock
        Place_Keyword: 13163 = Jefferson
        Place_Keyword: 13167 = Johnson
        Place_Keyword: 13175 = Laurens
        Place_Keyword: 13179 = Liberty
        Place_Keyword: 13183 = Long
        Place_Keyword: 13191 = Mclntosh
        Place_Keyword: 13267 = Tattnall
        Place_Keyword: 13279 = Toombs
        Place_Keyword: 13283 = Treutlen
        Place_Keyword: 13303 = Washington
        Place_Keyword: 13305 = Wayne
        Place_Keyword: 13319 = Wilkinson
    Access_Constraints: none
    Use_Constraints:
      none.  Acknowledgement of the U.S. Geological Survey and the
      National Geophysical Data Center would be appreciated
      in products derived from these data.
    Point_of_Contact:
      Contact_Information:
        Contact_Organization_Primary:
          Contact_Organization: USGS Gravity and Magnetics Contact
        Contact_Address:
          Address_Type: mailing address
          Address:
            U.S. Geological Survey
            Box 25046  Mail Stop 964
            Denver Federal Center
          City: Denver
          State_or_Province: CO
          Postal_Code: 80225
        Contact_Voice_Telephone: 303-236-1343
        Contact_Electronic_Mail_Address: grav_mag@usgs.gov
    Browse_Graphic:
      Browse_Graphic_File_Name: ftp://ftpmusette.cr.usgs.gov/pub/NA_MAGNETICS/digital_data/GA/GA_3048A.jpg
      Browse_Graphic_File_Description:
        An image of the flight lines showing total magnetic intensity
        along the flight lines.
      Browse_Graphic_File_Type: JPEG
    Data_Set_Credit:
      These USGS employees contributed to reformatting and archiving these data:

      Viki Bankey, Carol Finn, Pat Hill, Holly Hindle,
      Bob Kucks, Vicki Rystrom, Sarah Shearer

      Cooperating contributors from the National Geophysical Data Center are:

      Ronald Buhmann, David Dater, Susan McLean,
      Stewart Racey
    Native_Data_Set_Environment:
      These data were originally recorded on 9-track
      magnetic tapes and were transferred to CD-ROM.

      Data processing took place on an HP workstation
      running a Windows NT operating system.  Data
      were reformatted using the Geosoft, Inc., program
      Oasis Montaj version 4.3.
    Cross_Reference:
      Citation_Information:
        Originator: U.S. Geological Survey
        Publication_Date: 1999
        Title:
          Digitized Aeromagnetic Datasets of the Conterminous United States,
          Hawaii, and Puerto Rico
        Geospatial_Data_Presentation_Form: raster digital data
        Series_Information:
          Series_Name: U.S. Geological Survey Open-File Report
          Issue_Identification: 99-557
        Publication_Information:
          Publication_Place: Denver CO
          Publisher: U.S. Geological Survey
        Online_Linkage: http://greenwood.cr.usgs.gov/pub/open-file-reports/ofr-99-0557

    Cross_Reference:
      Citation_Information:
        Originator: Coastal Plains Regional Committee
        Originator: U.S. Geological Survey
        Publication_Date: 1976
        Title:
          Aeromagnetic maps of parts of Georgia, South Carolina,
          and North Carolina
        Geospatial_Data_Presentation_Form: map
        Series_Information:
          Series_Name: U.S. Geological Survey Open-File Report
          Issue_Identification: 76-191
        Publication_Information:
          Publication_Place: Denver, CO
          Publisher: U.S. Geological Survey
        Other_Citation_Details:
          map scale 1:250,000
          13 sheets
  Data_Quality_Information:
    Attribute_Accuracy:
      Attribute_Accuracy_Report:
        The data in this file have been processed using various formulas and
        methods that are not usually documented but that represent
        industry standard practices for airborne data reduction.  For example,
        position is listed as latitude and longitude, but these values
        were derived from the raw navigation data depending on the system used.
        (see notes under horizontal accuracy). Line numbers were added to
        records, and unusable data at flight-line ends were discarded
        (as aircraft slowed and turned around). Separate recordings were
        correlated by time and assigned to the correct location.

        The exact accuracies of these processing steps may not be known.
        They are discussed in the sections on attribute or positional
        accuracies.
    Logical_Consistency_Report:
      The data in this file were collected by a single contractor or group
      who were responsible for collecting and processing the data.

      The data from this survey were collected using the same instruments
      (magnetometers, altimeters, navigational systems) throughout
      the survey and were collected in a normal length of time with no long
      delays between survey beginning and end.

      Survey contracts specified the conditions and specifications under which
      these data were collected.  Standard industry practices of the time
      were followed in data collection and processing.
    Completeness_Report:
      This is survey part 1 of 2.  The second part of the survey can be found
      under West Georgia, Georgia, Project #3048B.  The survey was separated
      based on flight line direction (#3048A was flown along NW-SE lines, and
      #3048B was flown along N-S lines).

      Loss of data due to poor transmission, channel dropout, obvious spiking,
      missing channels, and other obvious errors were replaced with the
      value -9999.9, such as the radar and barom channels.

      The original data did not have flight line direction (directn), radar
      altimeter (radar), or barometric altimeter (barom) channels.  The flight
      line direction was manually calculated and added during USGS processing.

      The fiducial values have been multiplied by 100 in order to convert the
      original values to a format that complies with the established standard
      template.

      Residual magnetic values were adjusted on the following lines to eliminate
      obvious datum shifts within or between lines.
      Line number			Shift (nT)
      1				+45.5
      2				+45.5
      3				+45.5
      4				+45.5
      5				+45.5
      6 (northwest portion)		+45.5
      6 (south central portion)	-5
      6 (southeast portion)		-45.5
      7 (northwest portion)		+45.5
      7 (south central portion)	+5
      7 (southeast portion)		-45.5
      8 (northwest portion)		+45.5
      8 (south central portion)	+5
      8 (southeast portion)		-45.5
      9 (northwest portion)		+45.5
      9 (south central portion)	+5
      9 (southeast portion)		-45.5
      10 (northwest portion)		+45.5
      10 (south central portion)	+5
      10 (southeast portion)		-45.5
      11 (northwest portion)		+45.5
      11 (south central portion)	+5
      11 (southeast portion)		-45.5
      12 (northwest portion)		+45.5
      12 (south central portion)	+5
      12 (southeast portion)		-45.5
      13 (northwest portion)		+45.5
      13 (south central portion)	+5
      13 (southeast portion)		-45.5
      14 (northwest portion)		+45.5
      14 (south central portion)	+5
      14 (southeast portion)		-45.5
      15 (northwest portion)		+45.5
      15 (south central portion)	+5
      15 (southeast portion)		-45.5
      16 (northwest portion)		+45.5
      16 (south central portion)	+5
      16 (southeast portion)		-45.5
      17 (northwest portion)		+45.5
      17 (south central portion)	+5
      17 (southeast portion)		-45.5
      18 (northwest portion)		+45.5
      18 (south central portion)	+5
      18 (southeast portion)		-45.5
      19				+45.5
      20				+45.5
      21				+45.5
      22 (northwest portion)		+45.5
      22 (south central-east portion) -30
      23				+30
    Positional_Accuracy:
      Horizontal_Positional_Accuracy:
        Horizontal_Positional_Accuracy_Report:
          Flight Path Recovery

          Horizontal position of the survey aircraft used to collect
          data were determined by reconciling down-looking photographs
          (recorded on continuous-strip film) with topographic maps
          and orthophotoquadrangle maps.  Fiducial numbers and marks,
          impressed on any paper strips that were recording data or
          added to magnetic tape records, were included
          as a function of time to further reconcile location with
          instrumentation.

      Vertical_Positional_Accuracy:
        Vertical_Positional_Accuracy_Report:
          The aircraft vertical position was determined using the
          navigational positioning equipment on the aircraft, which
          were radar altimeter and barometric altimeter.

          Radar altimeters are estimated to have an error
          of 2-5% of the altitude (Richard Hansen, PRJ, Inc.,
          written communication).

          Barometric altimeters are quite accurate, but are
          typically operated in an uncorrected mode.  The
          diurnal variation in air pressure over the course of
          a flight can produce a 50-100 ft error in the
          barometric altimeter reading.  In addition, pressure microcells
          create short-period air pressure changes equivalent
          to about 10 ft under typical conditions (Richard
          Hansen, PRJ, Inc., written communication)

          This data set was collected at a draped survey having a
          average terrain clearance of 500 ft.  Because aircraft,
          especially airplanes, cannot safely maintain a constant
          terrain clearance, error in vertical position is
          introduced.
    Lineage:
      Process_Step:
        Process_Description:
          Conversion of measured values to geographic position and
          magnetic values was performed by the contractor using
          industry standard practices.

          Details are found under Attribute Accuracy Report,
          Horizontal_Position_Accuracy_Report, and
          Vertical_Position_Accuracy_Report

          Unless noted, conversion processes were not reported to the USGS.
          Unpublished products generated by the contractor included magnetic
          tapes, a map of residual or total field magnetics, and perhaps some
          written documentation.
        Process_Date: 1975
      Process_Step:
        Process_Description:
          USGS reformatting of contractor data to standard format.

          USGS personnel used the software package Oasis Montaj version 4.3 by
          Geosoft, Inc., to read in the original contractor's data.
          Latitude, longitude, altitude, and magnetic values were
          checked for obvious errors or spikes and values of -9999.9
          were given where the value could not be reasonably corrected.
          Other errors in the data were not corrected.  Horizontal positions
          were converted to latitude and longitude if the original values
          were UTM meters.  Elevations were converted from meters to feet
          (1 m = 3.2808 ft).  Information was added that was missing from the
          data file but was recorded elsewhere.  The reformatted data file was
          written in the format described in the section on
          Entity_and_Attribute_Overview.
        Process_Date: 20011212
  Spatial_Data_Organization_Information:
    Direct_Spatial_Reference_Method: point
  Spatial_Reference_Information:
    Horizontal_Coordinate_System_Definition:
      Geographic:
        Latitude_Resolution: .0001
        Longitude_Resolution: .0001
        Geographic_Coordinate_Units: decimal degrees
      Geodetic_Model:
        Horizontal_Datum_Name: North American Datum of 1927
        Ellipsoid_Name: Clarke 1866
        Semi-major_Axis: 6,378,206.4
        Denominator_of_Flattening_Ratio: 294.98
    Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
        Altitude_Datum_Name: National Geodetic Vertical Datum of 1929
        Altitude_Resolution: 1
        Altitude_Distance_Units: feet
        Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates
  Entity_and_Attribute_Information:
    Overview_Description:
      Entity_and_Attribute_Overview:
        >Airborne survey specifications
        >
        >These items are constant for the entire survey
        >
        >Project number: 3048A
        >Project name: East Georgia, Georgia
        >Survey flown by: Airborne Surveys, Inc.
        >Survey compiled by:  Geometrics, Inc.
        >Survey flown for: U.S. Geological Survey
        >Approx. no. of line miles: 5030
        >Survey height: 500 ft
        >Altitude method: Draped over terrain
        >Flight-line spacing: 1 mi
        >Flight-line direction: NW-SE
        >Aircraft used: Beechcraft E50 or Piper Navajo PA31
        >Airport - arrival: unknown
        >Airport - departure: unknown
        >Magnetometer used: Geometrics G-803 proton
        >Sensor tow distance: unknown
      Entity_and_Attribute_Detail_Citation:
        Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
        Geologists and Seismologists: Society of Exploration Geophysicists
        Monograph Series No. 1, p. 83-87.

        Dobrin, M.B., 1976, Introduction to Geophysical
        Prospecting: New York, McGraw-Hill Book Company,
        p. 505-517.
    Overview_Description:
      Entity_and_Attribute_Overview:
        >Each record contains the following 11 attributes:
        >
        >No abbrev.name contents
        >
        >1  line_no     flight line number
        >2  directn     flight line direction, azimuth degrees from north
        >(integer)
        >3  longitud    longitude (decimal degrees)
        >4  latitude    latitude (decimal degrees)
        >5  year        year flown (integer)
        >6  jul_day     Julian day flown (integer)
        >7  fiducial    fiducial number (integer)
        >8  radar       radar altimeter reading above ground (feet)
        >9  barom       altitude above mean sea level (feet)
        >10 totmag      corrected magnetic value (nT)
        >11 resmag      residual magnetic value (nT)
      Entity_and_Attribute_Detail_Citation:
        Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
        Geologists and Seismologists: Society of Exploration Geophysicists
        Monograph Series No. 1, p. 83-87.

        Dobrin, M.B., 1976, Introduction to Geophysical
        Prospecting: New York, McGraw-Hill Book Company,
        p. 505-517.
    Detailed_Description:
      Entity_Type:
        Entity_Type_Label: record for one magnetic data point
        Entity_Type_Definition:
          The set of all measurements reported for a magnetic data point
          having the same spatial location.
        Entity_Type_Definition_Source:
          Standard aeromagnetic data collection procedures as written in
          the contract for survey collection.
      Attribute:
        Attribute_Label: line_no
        Attribute_Definition: flight line number

        Attribute_Definition_Source: often assigned by airborne survey crew
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: 14
            Range_Domain_Maximum: 348
            Attribute_Units_of_Measure: alphanumeric value
      Attribute:
        Attribute_Label: directn
        Attribute_Definition:
          direction of flight line, azimuth degrees
          clockwise from north
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: 45
            Range_Domain_Maximum: 315
            Attribute_Units_of_Measure: degrees
      Attribute:
        Attribute_Label: longitud
        Attribute_Definition: longitude - geographic coordinate
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: -83.2822
            Range_Domain_Maximum: -81.0998
            Attribute_Units_of_Measure: decimal degrees
      Attribute:
        Attribute_Label: latitude
        Attribute_Definition: latitude - geographic coordinate
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: 31.1090
            Range_Domain_Maximum: 33.3703
            Attribute_Units_of_Measure: decimal degrees
      Attribute:
        Attribute_Label: year
        Attribute_Definition: year of data point collection
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: 1974
            Range_Domain_Maximum: 1975
      Attribute:
        Attribute_Label: jul_day
        Attribute_Definition:
          Julian day, where Jan. 1 = 1 and
          Dec. 31 = 365 or 366 (leap year)
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: 348
            Range_Domain_Maximum: 14
        Attribute_Value_Accuracy_Information:
          Attribute_Value_Accuracy: 31
          Attribute_Value_Accuracy_Explanation:
            Both beginning and end julian dates were taken from dataset.

            Since this survey took place into the following year (1974 and 1975),
            the minimum jul_day is 348 and the maximum jul_day is 14, based on
            calendar days.
      Attribute:
        Attribute_Label: fiducial
        Attribute_Definition:
          A fiducial number is a mark which indicates points of
          simultaneity.  It is a user-defined integer used during
          airborne operations to correlate recording devices (magnetometers)
          with navigational records (altimeters, camera film, strip charts)
          that were recorded at the same time.
        Attribute_Definition_Source:
          Sheriff, R.E., 1984, Encyclopedic dictionary of
          exploration geophysics: Tulsa, OK, Society of
          Exploration Geophysicists, p. 89.
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: 1987
            Range_Domain_Maximum: 999992
      Attribute:
        Attribute_Label: radar
        Attribute_Definition:
          radar altimetry reading, in feet

          An aircraft navigational system in which short electromagnetic waves
          are transmitted, and the energy scattered back by reflection
          is detected.  From this measurement, the distance between the aircraft
          and the ground is calculated and recorded as radar altimetry.

          Values of -9999.9 indicate missing data.
        Attribute_Definition_Source:
          Sheriff, R.E., 1984, Encyclopedic dictionary of exploration geophysics:
          Tulsa, OK, Society of Exploration Geophysicists, p. 89.
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: -9999.9
            Range_Domain_Maximum: -9999.9
            Attribute_Units_of_Measure: feet
      Attribute:
        Attribute_Label: barom
        Attribute_Definition:
          altitude above mean sea level, in feet, measured using the
          barometer that is part of the aircraft navigation system

          Values of -9999.9 indicate missing data.
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: -9999.9
            Range_Domain_Maximum: -9999.9
            Attribute_Units_of_Measure: feet
      Attribute:
        Attribute_Label: totmag
        Attribute_Definition:
          Raw magnetic value with base magnetometer corrections applied.

          Because the magnetic field of the earth varies diurnally,
          a stationary base magnetometer is maintained on the ground
          during airborne surveying.  The base magnetometer records
          changes in the magnetic field (in nanoTeslas) as a function
          of time.  The magnetic changes may have an amplitude of 20
          to 50 nanoTeslas.  If changes are more severe, as would
          occur from a magnetic storm, surveying is discontinued or
          the data recorded are not used.

          Diurnal variations are then removed from the airborne magnetic
          data based on the common time.

          Values of -9999.9 indicate missing data.
        Attribute_Definition_Source:
          see: Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
          Geologists and Seismologists: Society of Exploration Geophysicists
          Monograph Series No. 1, p. 83-87.

          A description of magnetometers and how they measure
          the total magnetic field can be found in:

          Dobrin, M.B., 1976, Introduction to Geophysical
          Prospecting: New York, McGraw-Hill Book Company,
          p. 505-517.
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: 51801.00
            Range_Domain_Maximum: 54194.00
            Attribute_Units_of_Measure: nanoTeslas
        Attribute_Value_Accuracy_Information:
          Attribute_Value_Accuracy: 2
          Attribute_Value_Accuracy_Explanation:
            The airborne magnetometer is accurate to about 1 nanoTesla,
            and the base magnetometer has the same accuracy.  The accuracy
            of the base-corrected airborne value therefore is near 2 nanoTeslas
            or better.
        Attribute_Measurement_Frequency:
          The magnetometer has a recharging interval of 0.5
          seconds.  The data were recorded at 1 second intervals.
      Attribute:
        Attribute_Label: resmag
        Attribute_Definition:
          residual magnetic value

          The total magnetic value minus a geomagnetic reference field (GRF),
          which is a long-wavelength regional magnetic field.  The most commonly
          used reference field is determined from a model developed by the
          International Association of Geomagnetism and Aeronomy (IAGA).  The
          International Geomagnetic Reference Field (IGRF), is a predictive model
          adopted at the beginning of a model period
          (e.g. in 1989 for 1990-1995).  After the model period, a revised
          definitive model is adopted, the DGRF.  This is the preferred model to
          use for removing regional magnetic fields.

          Temporal variations cannot be completely predicted, thus error arises
          in the application of the IGRF reductions.  These errors cannot be
          evaluated until the release of the DGRF, a minimum of five years after
          the IGRF release.  This field is issued to best describe the
          configuration of the earth's past magnetic field.

          Accuracy of the DGRF calculations is dependent on the quality of the
          survey data and sensitive to changes in air pressure.  Through
          processing experimentation and experience, USGS personnel found that
          significant flight altitude changes produced small changes (0.01-0.03
          nT) in DGRF values regardless of the altitude source used (e.g. radar
          altimeter, barometric altimeter).  If radar altimeter data are
          complete, a terrain channel was calculated using Oasis Montaj DAP
          (Data Access Protocol), USGS 1:250,000 terrain data, or USGS 15 second
          terrain data.  DAP is the easiest to use but suffers from inconvenient
          dummy values at sea level.  In such cases, 15 second terrain data was
          used.

          For this survey, the field removed was the DGRF 1975 calculated from
          the date and 15 second terrain data added to an altitude datum of 152
          meters (500 ft).

          Values of -9999.9 indicate missing data.
        Attribute_Definition_Source:
          Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
          Geologists and Seismologists: Society of Exploration Geophysicists
          Monograph Series No. 1, p. 83-87.
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: -632.04
            Range_Domain_Maximum: 522.78
            Attribute_Units_of_Measure: nanoTeslas
        Attribute_Value_Accuracy_Information:
          Attribute_Value_Accuracy: 2
          Attribute_Value_Accuracy_Explanation:
            The Geomagnetic Reference Field that was subtracted from
            the total magnetic value is based on a model, which was
            updated to the date of the survey.  New models are
            available at five year intervals.  These models have
            varying degrees of accuracy in determining the local
            reference field.
  Distribution_Information:
    Distributor:
      Contact_Information:
        Contact_Organization_Primary:
          Contact_Organization: CD-ROM distributor: USGS Information Services
        Contact_Address:
          Address_Type: mailing address
          Address:
            Box 25286, Building 810
            Denver Federal Center
          City: Denver
          State_or_Province: CO
          Postal_Code: 80225
        Contact_Voice_Telephone:
          303-202-4700
          or 1-888-ASK-USGS
        Contact_Electronic_Mail_Address: www.usgs.gov/pubprod
    Resource_Description: USGS Open-File Report OFR 02-0361
    Distribution_Liability:
      Although all data published on this CD-ROM have been used by the USGS,
      no warranty, expressed or implied, is made by the USGS as to the
      accuracy of the data and related materials.  The act of distribution
      shall not constitute any such warranty, and no responsibility is
      assumed by the USGS in the use of these data or related materials.

      Any use of trade, product, or firm names is for descriptive purposes
      only and does not imply endorsement by the U.S. Government.
    Standard_Order_Process:
      Digital_Form:
        Digital_Transfer_Information:
          Format_Name: ASCII
          Format_Specification:
            >Each line contains data in the following format,
            >beginning with line 1(no header included):
            >line_no       I5
            >directn       I4
            >longitud      F11.4
            >latitude      F9.4
            >year          I5
            >jul_day       I4
            >fiducial      I7
            >radar         F8.1
            >barom         F8.1
            >totmag        F9.2
            >resmag        F9.2, 1X
          Format_Information_Content: Magnetic anomaly measurements
          File_Decompression_Technique: gunzip
        Digital_Transfer_Option:
          Offline_Option:
            Offline_Media: CD-ROM
            Recording_Format: ISO 9660
      Fees:
        CD-ROM prices are subject to change. Please call or see
        http://mapping.usgs.gov/esic/prices/
      Ordering_Instructions:
        Detailed instructions can be found at
        www.usgs.gov/pubprod
  Distribution_Information:
    Distributor:
      Contact_Information:
        Contact_Organization_Primary:
          Contact_Organization:
            Web site administration: U.S Geological Survey
            Central Publications Group
        Contact_Address:
          Address_Type: mailing address
          Address:
            Central Publications Group
            USGS MS 902, Box 25046 DFC
          City: Denver
          State_or_Province: CO
          Postal_Code: 80225-0046
        Contact_Voice_Telephone: 303-236-5486
    Resource_Description: USGS Open-File Report OFR 02-0361
    Distribution_Liability:
      Although all data published on this CD-ROM have been used by the USGS,
      no warranty, expressed or implied, is made by the USGS as to the
      accuracy of the data and related materials.  The act of distribution
      shall not constitute any such warranty, and no responsibility is
      assumed by the USGS in the use of these data or related materials.

      Any use of trade, product, or firm names is for descriptive purposes
      only and does not imply endorsement by the U.S. Government.
    Standard_Order_Process:
      Digital_Form:
        Digital_Transfer_Information:
          Format_Name: ASCII
          Format_Specification:
            >Each line contains data in the following format,
            >beginning with line 1 (no header included):
            >line_no       I5
            >directn       I4
            >longitud      F11.4
            >latitude      F9.4
            >year          I5
            >jul_day       I4
            >fiducial      I7
            >radar         F8.1
            >barom         F8.1
            >totmag        F9.2
            >resmag        F9.2, 1X
          Format_Information_Content: Magnetic anomaly measurements
          File_Decompression_Technique: gunzip
        Digital_Transfer_Option:
          Online_Option:
            Computer_Contact_Information:
              Network_Address:
                Network_Resource_Name: ftp://ftpmusette.cr.usgs.gov/pub/NA_MAGNETICS/digital_data/GA/GA_3048A.xyz.gz
            Online_Computer_and_Operating_System:
              Hewlett Packard 9000/K220
              UNIX server running HPUX 11.00
      Fees: none
  Metadata_Reference_Information:
    Metadata_Date: 20020717
    Metadata_Contact:
      Contact_Information:
        Contact_Organization_Primary:
          Contact_Organization: USGS Gravity and Magnetics contact
        Contact_Address:
          Address_Type: mailing address
          Address:
            U.S. Geological Survey
            Box 25046 Mail Stop 964
            Denver Federal Center
          City: Denver
          State_or_Province: CO
          Postal_Code: 80225-0046
        Contact_Voice_Telephone: 303-236-1343
        Contact_Electronic_Mail_Address: grav_mag@usgs.gov
    Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
    Metadata_Standard_Version: FGDC-STD-001-1998