Identification_Information:
  Citation:
    Citation_Information:
      Originator: James A. Miller (comp.)
      Publication_Date: 19980701
      Title: Principal Aquifers of the 48 Contiguous United States
      Edition: Version 1.0
      Geospatial_Data_Presentation_Form: map
      Publication_Information:
        Publication_Place: Madison, Wisconsin, USA
        Publisher: U.S. Geological Survey
      Online_Linkage: <http://nationalatlas.gov/atlasftp.html>
  Description:
    Abstract:
      This data set contains the shallowest principal aquifers of the contiguous 
      United States, portrayed as polygons.  The data set was developed as part 
      of the effort to produce the maps published at 1:2,500,000 in the printed 
      series "Ground Water Atlas of the United States".  The published maps 
      contain base and cultural features not included in these data.
    Purpose:
      These data are intended for use in publications, at a scale of 1:2,500,000 
      or smaller.  Due to the small scale, the primary intended use is for 
      regional and national data display and analysis, rather than specific 
      local data analysis.
    Supplemental_Information:
      The Ground Water Atlas of the United States (GWA) chapters include 
      additional information that may be relevant to the use of this data set, 
      such as maps of alluvial and glacial aquifers that overlie the aquifers in 
      this data set, as well as other information described below. 

      The areal extent of the aquifers, as shown in this data set, represents 
      the area in which a named aquifer is the shallowest of the principal 
      aquifers.  These aquifer areas are not necessarily the only areas in which 
      ground water can be withdrawn, for two reasons:  1) The aquifers shown may 
      have a larger areal extent than is represented here.  The boundaries in 
      this data set generally represent an interpretation of the surface 
      location (outcrop), or near-surface location (shallow subcrop) of the 
      uppermost principal aquifer for the area.  An aquifer may extend beyond 
      the area shown, but be overlain by one or more other aquifers, and (or) 
      low-permeability material.  2) There may be areas of water-bearing 
      surficial material not shown in this data set.  Major alluvial aquifers 
      that occur along main watercourses are not shown.  Significant 
      unconsolidated sand and gravel aquifers, that are not indicated in this 
      data set but are important sources of water, may occur locally in 
      glaciated regions.  The user of this data set is advised that to get 
      complete information regarding areas that serve as sources of water, more
      information about surficial aquifers needs to be obtained, particularly in 
      glaciated areas.

      This data set was constructed by combining data created for or from the 
      regional GWA chapters.  Minor aquifers that are important local sources of 
      water were mapped in some regions, so the regional maps in the GWA may 
      show more detail than this data set.  The juxtaposition of regionally
      mapped aquifers has led to some instances where an aquifer outcrop or 
      shallow subcrop is bounded by a State line.  This is a result of the 
      regional mapping and national categorization methods used and is not meant 
      to imply a hydrogeologic change coincident with a State boundary.

      The aquifer outcrop and shallow subcrop boundaries represent broad, 
      regional categories and should not be interpreted as site-specific.  
      Comments regarding the names of aquifers or the hydrogeologic 
      interpretation of the aquifers can be directed to the U.S. Geological 
      Survey, Water Resources Division, Office of Ground Water, Roy
      Sonenshein, sunshine@usgs.gov, (305) 717-5824.

      This data set was used as part of the effort to publish a 1:5,000,000-
      scale 'Principal Aquifers' map in the National Atlas of the United States 
      of America series of printed maps.  The printed map can be considered  a 
      representation of this data set with the exceptions of: the smaller scale,
      slight differences in the coastline due to generalization, base and 
      cultural information, and delineation of the glacial-deposit area.

      These data were developed in conjunction with the publication of the GWA.  
      For documentation purposes, areas are referred to by their corresponding 
      GWA chapter letter, or by State.  This list shows the relationship between
      State names and GWA chapters:
      >HA 730-B        Segment 1-California, Nevada
      >HA 730-C        Segment 2-Colorado, Utah, New Mexico, Arizona
      >HA 730-D        Segment 3-Kansas, Missouri, Nebraska
      >HA 730-E        Segment 4-Texas, Oklahoma
      >HA 730-F        Segment 5-Arkansas, Louisiana, Mississippi
      >HA 730-G        Segment 6-Alabama, Florida, Georgia, South Carolina
      >HA 730-H        Segment 7-Idaho, Oregon, Washington
      >HA 730-I        Segment 8-Montana, North Dakota, South Dakota, Wyoming
      >HA 730-J        Segment 9-Iowa, Michigan, Minnesota, Wisconsin
      >HA 730-K        Segment 10-Illinois, Indiana, Kentucky, Ohio, Tennessee
      >HA 730-L        Segment 11-Delaware, Maryland, New Jersey, North 
      >                           Carolina, Pennsylvania, Virginia, West 
      >                           Virginia
      >HA 730-M        Segment 12-Connecticut, Maine, Massachusetts, New 
      >                           Hampshire, New York, Rhode Island, Vermont
      Refer to <http://capp.water.usgs.gov/gwa/gwa.html> for a graphic depiction 
      of the GWA chapter regions, as well as more information about the GWA.

      Although these spatial data can stand alone, it may be helpful to refer to 
      the printed GWA chapters when using the data.  There are three subject 
      areas in which there are significant differences between this data set and 
      the printed chapters: category changes, which are described below; 
      coastline location, and the representation of aquifers in Western Montana, 
      both of which are discussed in the Process Description under Lineage.

      Category Changes

      Because the GWA regional chapters were written by different authors, there 
      were areas of different interpretations and category delineations, aquifer 
      names, etc., that became apparent when combining the regions.  In most 
      cases, the name and delineation of the aquifer is identical between this 
      data set and the GWA printed maps, but there are several areas of 
      differences.  In some cases, a single aquifer from a GWA chapter is 
      represented among multiple aquifers in this data set.

      The following listings show the differences between aquifer names in the 
      GWA chapters and the aq_name and aq_code used in this data set.  See the 
      Entity and Attribute Information section for definitions of the data 
      attributes.

      >GWA chapter HA 730-B
      >Name from fig 11, page B4     aq_code-aq_name
      >____________________________________________________________
      >Basin and Range volcanic-     601-Southern Nevada
      >rock aquifers                     volcanic-rock aquifers
      >
      >Coastal Basins aquifers       103-California Coastal Basin
      >                                  aquifers
      >
      >Northern California Basin     104-Pacific Northwest
      >fill aquifers                     basin-fill aquifers
      >
      >
      >GWA chapter HA 730-C
      >Name from fig 11, page C4
      >____________________________________________________________
      >Names and categories the same
      >
      >
      >GWA chapter HA 730-D
      >Name from fig 5, page D4      aq_code-aq_name
      >____________________________________________________________
      >Mississippi embayment         109-Mississippi River Valley
      >aquifer system                    alluvial aquifer
      >
      >Great Plains aquifer          304-Lower Cretaceous
      >                                  aquifers system      
      >
      >Confining unit                999-Not a principal aquifer
      >
      >Not a principal aquifer       999-Not a principal aquifer
      >
      >Dune sand                     107-High Plains aquifer
      >
      >
      >GWA chapter HA 730-E
      >Name from fig 4, page E3      aq_code-aq_name
      >____________________________________________________________
      >EDWARDS-TRINITY AQUIFER SYSTEM
      >Edwards-Trinity aquifer       501-Edwards-Trinity aquifer
      >                                  system
      >
      >Edwards aquifer               501-Edwards-Trinity aquifer
      >                                  system
      >
      >Trinity aquifer               501-Edwards-Trinity aquifer
      >                                  system
      >
      >Confining unit                999-Not a principal aquifer
      >
      >
      >GWA chapter HA 730-F
      >Name from fig 7, page 4       aq_code-aq_name
      >____________________________________________________________
      >MAJOR AQUIFER SYSTEMS
      >Surficial aquifer system      109-Mississippi River Valley
      >                                  alluvial aquifer
      >                              203-Mississippi embayment
      >                                  aquifer system
      >                              501-Edwards-Trinity aquifer
      >                                  system
      >                              999-Not a principal aquifer
      >
      >Mississippi embayment         109-Mississippi River Valley
      >aquifer system                    alluvial aquifer
      >                              203-Mississippi embayment
      >                                  aquifer
      >                              204-Southeastern Coastal
      >                                  Plain aquifer system
      >                              999-Not a principal aquifer
      >
      >MINOR AQUIFERS AND AQUIFER SYSTEMS - Aquifer systems in
      >rocks of cretaceous age
      >Edwards-Trinity aquifer       501-Edwards-Trinity aquifer
      >system (Trinity aquifer)          system
      >
      >Tokio-Woodbine aquifer        999-Not a principal aquifer
      >
      >Ouachita Mountains aquifer    999-Not a principal aquifer
      >
      >CONFINING SYSTEMS AND CONFINING UNITS
      >Western Interior Plains       999-Not a principal aquifer
      >confining systems
      >
      >Confining unit                109-Mississippi River Valley
      >                                  alluvial aquifer
      >                              203-Mississippi embayment
      >                                  aquifer system
      >                              999-Not a principal aquifer
      >
      >
      >GWA chapter HA 730-G
      >Name from fig 3, page 3       aq_code-aq_name
      >____________________________________________________________
      >Sand and gravel aquifer       201-Coastal lowlands aquifer
      >                                  system
      >
      >Piedmont and Blue Ridge       999-Not a principal aquifer
      >aquifers
      >
      >Appalachian Plateaus          310-Pennsylvanian aquifers
      >aquifers
      >
      >Interior Low Plateaus         503-Mississippian aquifers
      >aquifers
      >
      >Confining unit                999-Not a principal aquifer
      >
      >
      >GWA chapter HA 730-H
      >Name from fig 5, page H4      aq_code-aq_name
      >____________________________________________________________
      >Unconsolidated-deposit        104-Pacific Northwest
      >aquifers                          basin-fill aquifers
      >                              112-Puget-Willamette Lowland
      >                                  aquifer system
      >                              105-Northern Rocky Mountains
      >                                  Intermontane basins
      >                                  aquifer system
      >                              101-Basin and Range aquifers
      >
      >Pliocene and younger          603-Pliocene and younger
      >basaltic-rock aquifers            basaltic-rock aquifers
      >                              606-Snake River Plain
      >                                  aquifer system
      >
      >Miocene basaltic-rock         607-Columbia Plateau aquifer
      >aquifers                          system
      >                              604-Miocene basaltic-rock
      >                                  aquifers
      >
      >Aquifers in pre-Miocene       401-Basin and Range
      >rocks                             carbonate-rock aquifers
      >                              999-Not a principal aquifer
      >
      >
      >GWA chapter HA 730-I.  See Process Description regarding
      >differences between this data and the printed Ground Water
      >Atlas chapter in Western Montana
      >Name from fig 7, page I4      aq_code-aq_name
      >____________________________________________________________
      >Quaternary volcanic and       605-Volcanic and 
      >sedimentary rock aquifers         sedimentary-rock
      >                                  aquifers
      >
      >Upper Tertiary aquifers       107-High Plains aquifer
      >                              316-Wyoming Tertiary
      >                                  aquifers
      >
      >Lower Tertiary aquifers       107-High Plains aquifer
      >                              314-Lower Tertiary aquifers
      >
      >Upper Cretaceous aquifers     301-Colorado Plateaus
      >                                  aquifers
      >                              315-Upper Cretaceous
      >                                  aquifers
      >
      >Lower Cretaceous aquifers     301-Colorado Plateaus
      >                                  aquifers
      >                              304-Lower Cretaceous aquifer
      >
      >Confining unit                301-Colorado Plateaus
      >                                  aquifers
      >
      >
      >GWA chapter HA 730-J
      >Name from fig 7, page J4      aq_code-aq_name
      >____________________________________________________________
      >Cretaceous aquifer            304-Lower Cretaceous
      >                                  aquifers
      >
      >MISSISSIPPIAN AQUIFER
      >Carbonate rocks               503-Mississippian aquifers
      >
      >Sandstone                     311-Mississippian aquifers
      >                                  of Michigan
      >
      >Crystalline-rock aquifer      999-Not a principal aquifer
      >
      >Confining unit                999-Not a principal aquifer
      >
      >
      >GWA chapter HA 730-K
      >Name from fig 5, page K4      aq_code-aq_name
      >____________________________________________________________
      >Blue Ridge aquifers           308-Early Mesozoic basin
      >                                  aquifers
      >                              999-Not a principal aquifer
      >
      >MISSISSIPPI EMBAYMENT AQUIFER SYSTEM
      >Upper Claiborne, middle       203-Mississippi embayment
      >Claiborne, middle Wilcox,         aquifer system
      >and lower Wilcox              109-Mississippi River Valley
      >                                  alluvial aquifer
      >
      >McNairy-Nacatoch              204-Southeastern Coastal
      >                                  Plain aquifer system
      >
      >Confining unit                999-Not a principal aquifer
      >
      >
      >GWA chapter HA 730-L
      >Name from fig 7, page L4      aq_code-aq_name
      >____________________________________________________________
      >NORTHERN ATLANTIC COASTAL PLAIN AQUIFER SYSTEM
      >Surficial aquifer             111-Surficial aquifer system
      >
      >Chesapeake aquifer            205-Northern Atlantic
      >                                  Coastal Plain aquifer
      >                                  system
      >
      >Castle Hayne-Aquia aquifer    418-Castle Hayne aquifer
      >
      >Severn-Magothy aquifer        205-Northern Atlantic
      >                                  Coastal Plain aquifer
      >                                  system
      >
      >Peedee-upper Cape Fear        205-Northern Atlantic
      >aquifer                           Coastal Plain aquifer
      >                                  system
      >
      >Potomac aquifer               205-Northern Atlantic
      >                                  Coastal Plain aquifer
      >                                  system
      >
      >PIEDMONT AND BLUE RIDGE AQUIFERS
      >Aquifers in early Mesozoic    308-Early Mesozoic basin
      >basins                            aquifers
      >
      >Carbonate-rock aquifers       417-Piedmont and Blue Ridge
      >                                  carbonate-rock aquifers
      >
      >Crystalline-rock aquifers     999-Not a principal aquifer
      >
      >Valley and Ridge              505-Valley and Ridge
      >carbonate-rock aquifers           carbonate-rock aquifers
      >                              416-New York and New England
      >                                  carbonate-rock aquifers
      >
      >APPALACHIAN PLATEAUS
      >Permian and Pennsylvanian     310-Pennsylvanian aquifers
      >aquifers
      >
      >
      >GWA chapter HA 730-M
      >Name from fig 10, page M5     aq_code-aq_name
      >____________________________________________________________
      >CARBONATE-ROCK AQUIFERS
      >New York and New England      416-New York and New England
      >                                  carbonate-rock aquifers
      >
      >Valley and Ridge              416-New York and New England
      >                                  carbonate-rock aquifers
      >
      >SANDSTONE AQUIFERS
      >Mesozoic sandstone and        308-Early Mesozoic basin
      >basalt of the Newark              aquifers
      >Supergroup
      >
      >Lower Paleozoic               309-New York sandstone
      >                                  aquifers
      >
      >CRYSTALLINE-ROCK AQUIFERS
      >Adirondack                    999-Not a principal aquifer
      >
      >New England                   999-Not a principal aquifer
      >
      >
      Related Spatial and Tabular Data Sets

      A data set showing the extent of glacial deposits is included in the 
      online, interactive National Atlas of the United States, but is not 
      available to download.  This data set shows the southern limit of 
      glaciation in the United States; areas north of the limit line may contain
      significant sand and gravel glacial deposits that are important sources of 
      water for local areas.

      A data set of aquifers of Alaska is in work.

      A data set of aquifers of Puerto Rico and the U.S. Virgin Islands is in 
      work.

      A data set of aquifers of Hawaii is planned.

      The final data are being served to the public in the following formats: 
      Spatial Data Transfer Standard (SDTS), Arc/INFO Export, or ArcView 
      Shapefile.
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 19980701
    Currentness_Reference: publication date
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: As needed
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -124.7559077
      East_Bounding_Coordinate: -66.93956058
      North_Bounding_Coordinate: 49.38561903
      South_Bounding_Coordinate: 24.51832172
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: None
      Theme_Keyword: aquifer
      Theme_Keyword: groundwater
      Theme_Keyword: hydrogeology 
      Theme_Keyword: geohydrology
    Place:
      Place_Keyword_Thesaurus: None
      Place_Keyword: Alabama
      Place_Keyword: Arizona
      Place_Keyword: Arkansas
      Place_Keyword: California
      Place_Keyword: Colorado
      Place_Keyword: Connecticut
      Place_Keyword: Delaware
      Place_Keyword: District of Columbia
      Place_Keyword: Florida
      Place_Keyword: Georgia
      Place_Keyword: Idaho
      Place_Keyword: Illinois
      Place_Keyword: Indiana
      Place_Keyword: Iowa
      Place_Keyword: Kansas
      Place_Keyword: Kentucky
      Place_Keyword: Louisiana
      Place_Keyword: Maine
      Place_Keyword: Maryland
      Place_Keyword: Massachusetts
      Place_Keyword: Michigan
      Place_Keyword: Minnesota
      Place_Keyword: Mississippi
      Place_Keyword: Missouri
      Place_Keyword: Montana
      Place_Keyword: Nebraska
      Place_Keyword: Nevada
      Place_Keyword: New Hampshire
      Place_Keyword: New Jersey
      Place_Keyword: New Mexico
      Place_Keyword: New York
      Place_Keyword: North Carolina
      Place_Keyword: North Dakota
      Place_Keyword: Ohio
      Place_Keyword: Oklahoma
      Place_Keyword: Oregon
      Place_Keyword: Pennsylvania
      Place_Keyword: Rhode Island
      Place_Keyword: South Carolina
      Place_Keyword: South Dakota
      Place_Keyword: Tennessee
      Place_Keyword: Texas
      Place_Keyword: Utah
      Place_Keyword: Vermont
      Place_Keyword: Virginia
      Place_Keyword: Washington
      Place_Keyword: West Virginia
      Place_Keyword: Wisconsin
      Place_Keyword: Wyoming
      Place_Keyword: United States
  Access_Constraints: None
  Use_Constraints: 
    None.  Acknowledgment of the Ground Water Atlas of the United States and 
    (or) the National Atlas of the United States of America would be appreciated 
    in products derived from these data.
  Point_of_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
        Contact_Person: 
          Chief, Cartographic and Publications Program, Water Resources Division
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 505 Science Drive
        City: Madison
        State_or_Province: WI
        Postal_Code: 53711-1061
        Country: USA
      Contact_Voice_Telephone: 608-238-9333
  Data_Set_Credit:
    This data set was created and modified over a period of at least five years 
    by several staff members of the U.S. Geological Survey Water Resources 
    Division Cartographic and Publications Program in Madison, Wisconsin.  
    Completion of this data set and associated metadata was funded, in part, 
    under a cooperative joint funding agreement between the U.S. Geological 
    Survey and the U.S. Environmental Protection Agency.
  Native_Data_Set_Environment: 
    Data General UNIX, Arc/INFO Version 7.04 coverage; and ESRI Shapefile format

Data_Quality_Information:
  Logical_Consistency_Report:
    Polygon and chain-node topology are present.  Each polygon is closed and has 
    one label point.
  Completeness_Report: 
    This data set includes aquifer information for the 48 contiguous United 
    States.
  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Planert, M. (comp.)
          Originator: Williams, J.S. (comp.)
          Publication_Date: 1995
          Title: 
            Ground Water Atlas of the United States-Segment 1: California, 
            Nevada
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-B
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1995
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-B
      Source_Contribution: Aquifer data for California and Nevada
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Robson, S.G. (comp.)
          Originator: Banta, E.R. (comp.)
          Publication_Date: 1995
          Title: 
            Ground Water Atlas of the United States-Segment 2: Arizona, 
            Colorado, New Mexico, Utah
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-C
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1995
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-C
      Source_Contribution: 
        Aquifer data for Arizona, Colorado, New Mexico, and Utah
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Miller, J.A. (comp.)
          Originator: Appel, C.L. (comp.)
          Publication_Date: 1998
          Title: 
            Ground Water Atlas of the United States-Segment 3: Kansas, Missouri, 
            Nebraska
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-D
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1998
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-D
      Source_Contribution: Aquifer data for Kansas, Missouri, and Nebraska
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Ryder, P.D. (comp.)
          Publication_Date: 1996
          Title: 
            Ground Water Atlas of the United States-Segment 4: Oklahoma, Texas
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-E
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1996
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-E
      Source_Contribution: Aquifer data for Oklahoma and Texas
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Renken, R.A. (comp.)
          Publication_Date: 1998                  
          Title: 
            Ground Water Atlas of the United States-Segment 5: Arkansas, 
            Louisiana, Mississippi
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-F
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1998
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-F
      Source_Contribution: Aquifer data for Arkansas, Louisiana, and Mississippi
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Miller, J.A. (comp.)
          Publication_Date: 1990
          Title: 
            Ground Water Atlas of the United States-Segment 6: Alabama, Florida, 
            Georgia, and South Carolina
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-G
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1990
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-G
      Source_Contribution: 
        Aquifer data for Alabama, Florida, Georgia, and South Carolina
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Whitehead, R.L. (comp.)
          Publication_Date: 1994
          Title: 
            Ground Water Atlas of the United States-Segment 7: Idaho, Oregon, 
            Washington
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-H
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1994
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-H
      Source_Contribution: Aquifer data for Idaho, Oregon, and Washington
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Whitehead, R.L. (comp.)
          Publication_Date: 1996
          Title: 
            Ground Water Atlas of the United States-Segment 8: Montana, North 
            Dakota, South Dakota, Wyoming
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-I
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1996
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-I
      Source_Contribution: 
        Aquifer data for Montana, North Dakota, South Dakota, and Wyoming
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Olcott, P.G. (comp.)
          Publication_Date: 1992
          Title: 
            Ground Water Atlas of the United States-Segment 9: Iowa, Michigan, 
            Minnesota, Wisconsin
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-J
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1992
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-J
      Source_Contribution: 
        Aquifer data for Iowa, Michigan, Minnesota, and Wisconsin
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Lloyd, O.B., Jr. (comp.)
          Originator: Lyke, W.L. (comp.)
          Publication_Date: 1995
          Title: 
            Ground Water Atlas of the United States-Segment 10: Illinois, 
            Indiana, Kentucky, Ohio, Tennessee
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-K
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1995
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-K
      Source_Contribution: 
        Aquifer data for Illinois, Indiana, Kentucky, Ohio, and Tennessee
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Trapp, H., Jr. (comp.)
          Originator: Horn, M.A. (comp.)
          Publication_Date: 1997
          Title: 
            Ground Water Atlas of the United States-Segment 11: Delaware, 
            Maryland, New Jersey, North Carolina, Pennsylvania, Virginia, West 
            Virginia
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-L
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1997
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-L
      Source_Contribution: 
        Aquifer data for Delaware, Maryland, New Jersey, North Carolina, 
        Pennsylvania, Virginia, and West Virginia
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: Olcott, P.G. (comp.)
          Publication_Date: 1995
          Title: 
            Ground Water Atlas of the United States-Segment 12: Connecticut, 
            Maine, Massachusetts, New Hampshire, New York, Rhode Island, Vermont
          Edition: 1.0
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: Hydrologic Investigations Atlas
            Issue_Identification: HA 730-M
          Publication_Information:
            Publication_Place: Reston,VA
            Publisher: U.S. Geological Survey
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: stable-base material
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1995
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: GWA HA 730-M
      Source_Contribution: 
        Aquifer data for Connecticut, Maine, Massachusetts, New Hampshire, New 
        York, Rhode Island, and Vermont
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: United States Geological Survey
          Publication_Date: 1998
          Title: State Boundaries
          Geospatial_Data_Presentation_Form: map
          Publication_Information:
            Publication_Place: Reston,VA
            Publisher: U.S. Geological Survey
          Online_Linkage: <http://nationalatlas.gov/atlasftp.html>
      Source_Scale_Denominator: 2000000
      Type_of_Source_Media: online
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1997
        Source_Currentness_Reference: publication date
      Source_Citation_Abbreviation: DLG State boundaries
      Source_Contribution: Coastline and international boundary
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey, Water Resources Division
          Publication_Date: Unpublished material
          Title: National aquifers file
          Geospatial_Data_Presentation_Form: map
      Source_Scale_Denominator: 2500000
      Type_of_Source_Media: internal file
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Range_of_Dates/Times:
            Beginning_Date: 1990
            Ending_Date: 1993
        Source_Currentness_Reference: publication or compilation date
      Source_Citation_Abbreviation: National aquifers file
      Source_Contribution: Preliminary aquifer map of the 48 contiguous States.
    Process_Step:
      Process_Description:  
        Aquifer outcrop line work for each GWA chapter was compiled on mylar at 
        a scale of 1:2,000,000, and reduced to 1:2,500,000 for further
        production work.  For chapters HA 730-G, -H, and -J, the outcrop lines 
        were scribed at a line width of 0.006 inch.  Film positives made from 
        the scribed materials were scanned on a drum scanner, vectorized, and 
        converted to Arc/INFO coverages.  For chapters HA 730-B, -C, -D, -E, -F, 
        -I, -K, -L, and -M, the aquifer compilation was either hand digitized, 
        and (or) scanned on a drum scanner, vectorized and converted to Arc/INFO 
        coverages.  The data were then checked, cleaned up, and attribute
        creation was done.

        The Arc/INFO coverages were plotted and checked against the source 
        compilations.  Polygons were attributed using Arcedit.  The coverages 
        for GWA chapters HA 730-B, -C, -D, -E, -F, -I, -K, -L, and -M were used 
        to generate output files that were imported into Adobe Illustrator
        for map publication.  Each completed map, at a scale of 1:2,500,000, was 
        reviewed for content and accuracy by the chapter lead cartographer, 
        Water Resources Division Geohydrologic Map Editor, and chapter author.

        Individual chapter coverages were appended into one continuous coverage.  
        Arcedit was used for edgematching and to remove duplicate labels.  No 
        DISSOLVE was done on the coverage; an equivalent of a DISSOLVE was done
        manually in Arcedit in conjunction with attribute checking, by removing 
        arcs that divided adjacent polygons with the same attributes.  Several 
        iterations of editing were performed.  These mostly involved ensuring 
        all polygons had labels and aquifer information and ensuring polygons 
        had correct aquifer information.  No polygons were removed for 
        generalization.
      Source_Used_Citation_Abbreviation: HA 730-B
      Source_Used_Citation_Abbreviation: HA 730-C
      Source_Used_Citation_Abbreviation: HA 730-D
      Source_Used_Citation_Abbreviation: HA 730-E
      Source_Used_Citation_Abbreviation: HA 730-F
      Source_Used_Citation_Abbreviation: HA 730-G
      Source_Used_Citation_Abbreviation: HA 730-H
      Source_Used_Citation_Abbreviation: HA 730-I
      Source_Used_Citation_Abbreviation: HA 730-J
      Source_Used_Citation_Abbreviation: HA 730-K
      Source_Used_Citation_Abbreviation: HA 730-L
      Source_Used_Citation_Abbreviation: HA 730-M
      Source_Produced_Citation_Abbreviation: National aquifers file
      Process_Date: 1993
    Process_Step:
      Process_Description:  
        Plots of the national aquifers file were made at 1:2,500,000, covering 
        the areas of the regional GWA chapters.  Each plot was compared to the
        printed GWA chapter aquifer maps.  Where applicable (chapters HA 730-B, 
        -C, -D, -E, -F, -I, -K, - L, and -M), an Adobe Illustrator file of the 
        coverage data was compared on-screen with the Illustrator file used to
        print the published map.  Discrepancies between the coverage file and 
        print file were noted, and the coverage updated to match the published 
        map.  Where a line appeared to shift noticeably (approximately 1/8 inch 
        at a scale of 1:2,500,000) across the boundary of two adjacent GWA 
        chapter regions, the line was adjusted for a smoother appearance.  The 
        adjustments may have been made on one or both sides of the region 
        boundary, depending on a cartographic assessment of the instance.

        Coastline Location

        The 1:2,500,000 principal aquifer maps in the Ground Water Atlas 
        publications used a coastline and international boundary, derived either 
        from the map separates from the National Atlas of the United States of
        America (published 1970), or from the Digital Line Graph (DLG) data 
        created from the 1970 National Atlas.  GWA chapters HA 730-G, -J, and -H 
        used coastline and boundary filmwork  photo-mechanically reduced from 
        the 1:2,000,000 National Atlas map separates.  The remaining chapters
        used coastline and boundary data from the DLG's.  A revision of the DLG 
        data took place in 1997, after the creation of the chapter aquifer map 
        data. 
 
        After the edgematching, a decision was made to replace the coast and 
        international boundary of this national-level aquifer data with one 
        derived from a newer version of 1997 DLG data.  State boundary data from 
        the U.S. Geological Survey National Mapping Division was used to provide 
        the coastline and two aquifer boundaries that coincide with State lines.  
        A publicly available version of this data and its metadata (Map Layer 
        Theme: States) can be found at <http://nationalatlas.gov/atlasftp.html>.

        The existing outline (coastline and international boundary line) was 
        removed, the new outline added to the coverage, and the remaining 
        aquifer contact lines snapped to the new outline.  The coverage was re-
        cleaned, data categories checked onscreen and with plots, and corrected.  
        Line and labeling corrections, such as undershoots, overshoots, and 
        improper labels were corrected in Arcedit.

        There are some slight locational differences between this data set and 
        the printed GWA chapters.  For example, there are  several small 
        differences in the number of small islands in coastal areas and the 
        categorization of these small islands was assigned to either the nearby
        principal aquifer category or as Not a principal aquifer, depending on 
        the location and categorization of similar small islands in the printed 
        GWA chapters.  There are other differences in the categorization of some
        land/shoreline-related features. For example, an area symbolized as a 
        bay in a GWA chapter may be land in this data set.

        Western Montana

        During the review of a printed map made from this national-level aquifer 
        data, the compiler, James A. Miller, requested a change in the 
        representation of aquifers in western Montana.  The area affected is in 
        the following counties: Lincoln, Flathead, Sanders, Lake, Mineral, 
        Missoula, Powell, Ravalli, Granite, Lewis and Clark, Deer Lodge, Silver 
        Bow, Jefferson,  Broadwater, Gallatin, Beavershead, and Madison.  These 
        areas fall under the Northern Rocky Mountain Intermontane Basins 
        Regional Aquifer Systems Analysis (RASA).  With one exception, the 
        aquifers, as shown in GWA chapter I, figure 7 in the listed counties 
        were removed and replaced with unconsolidated-deposit areas as shown in 
        GWA chapter HA 730-I, figure 6.  The exception is an area in northern
        Flathead county, listed as an Upper Tertiary aquifer in GWA chapter I, 
        figure 7, that was retained as an area but reclassified as a Lower 
        Tertiary aquifer.
      Source_Used_Citation_Abbreviation: National aquifer file
      Source_Used_Citation_Abbreviation: HA 730-B
      Source_Used_Citation_Abbreviation: HA 730-C
      Source_Used_Citation_Abbreviation: HA 730-D
      Source_Used_Citation_Abbreviation: HA 730-E
      Source_Used_Citation_Abbreviation: HA 730-F
      Source_Used_Citation_Abbreviation: HA 730-G
      Source_Used_Citation_Abbreviation: HA 730-H
      Source_Used_Citation_Abbreviation: HA 730-I
      Source_Used_Citation_Abbreviation: HA 730-J
      Source_Used_Citation_Abbreviation: HA 730-K
      Source_Used_Citation_Abbreviation: HA 730-L
      Source_Used_Citation_Abbreviation: HA 730-M
      Source_Used_Citation_Abbreviation: DLG State boundaries
      Process_Date: 1997

Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Vector
  Point_and_Vector_Object_Information:
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: Area point
      Point_and_Vector_Object_Count: 4276
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: Complete chain
      Point_and_Vector_Object_Count: 6802
    SDTS_Terms_Description:
      SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains
      Point_and_Vector_Object_Count: 4276

Spatial_Reference_Information: 
  Horizontal_Coordinate_System_Definition: 
    Geographic: 
      Latitude_Resolution: 0.000278  
      Longitude_Resolution: 0.000278  
      Geographic_Coordinate_Units: Decimal degrees 
    Geodetic_Model: 
      Horizontal_Datum_Name: North American Datum of 1983 
      Ellipsoid_Name: GRS1980
      Semi-major_Axis: 6378137.0 
      Denominator_of_Flattening_Ratio: 298.257222

Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: Aquifer (described by aquifrp025.pat or aquifrp025.dbf)
      Entity_Type_Definition: 
        A formation, group of formations, or part of a formation that contains 
        sufficient saturated permeable material to yield significant quantities 
        of water to wells and springs.
      Entity_Type_Definition_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: Shape
      Attribute_Definition: The representation of the entity in the data.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: Polygon
          Enumerated_Domain_Value_Definition: 2-dimensional element.
          Enumerated_Domain_Value_Definition_Source: ESRI GIS software
    Attribute:
      Attribute_Label: Area
      Attribute_Definition: The size of the shape in coverage units.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0.00000
          Range_Domain_Maximum: 56.31950
    Attribute:
      Attribute_Label: Perimeter
      Attribute_Definition: The perimeter of the shape in coverage units.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
       Range_Domain:
          Range_Domain_Minimum: 0.01024
          Range_Domain_Maximum: 606.75187
    Attribute:
      Attribute_Label: Aquifrp025# or Aquifrp025
      Attribute_Definition: Internal feature number.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 2
          Range_Domain_Maximum: 4277
    Attribute:
      Attribute_Label: Aquifrp025-ID (Export format only)
      Attribute_Definition: User-assigned feature number.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 4276
    Attribute:
      Attribute_Label: Rock_name
      Attribute_Definition: 
        The name of the permeable geologic material that composes the aquifer.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: unconsolidated sand and gravel aquifers
          Enumerated_Domain_Value_Definition: 
            Formations composed of loose sand and gravel.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: semiconsolidated sand aquifers
          Enumerated_Domain_Value_Definition: 
            Formations composed of partially solidified sand.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: sandstone aquifers
          Enumerated_Domain_Value_Definition: Formations composed of sandstone.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: Carbonate-rock aquifers
          Enumerated_Domain_Value_Definition: 
            Formations composed of limestone and (or) dolomite.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: Sandstone and carbonate-rock aquifers
          Enumerated_Domain_Value_Definition: 
            Formations composed of sandstone, limestone, and (or) dolomite.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: Basalt and other volcanic-rock aquifers
          Enumerated_Domain_Value_Definition: 
            Formations composed of volcanic rocks.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: (blank field)
          Enumerated_Domain_Value_Definition: 
            Not a principal aquifer.  Rocks that are generally poorly permeable
            but locally may contain productive aquifers.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: Rock_type
      Attribute_Definition: The code number relating to the rock_name.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 0
          Enumerated_Domain_Value_Definition: 
            Null value, assigned to null polygon.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 100
          Enumerated_Domain_Value_Definition: 
            Number for unconsolidated sand and gravel aquifers.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 200
          Enumerated_Domain_Value_Definition: 
            Number for semiconsolidated sand aquifers.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 300
          Enumerated_Domain_Value_Definition: Number for sandstone aquifers.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 400
          Enumerated_Domain_Value_Definition: 
            Number for carbonate-rock aquifers.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 500
          Enumerated_Domain_Value_Definition: 
            Number for sandstone and carbonate-rock aquifers.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 600
          Enumerated_Domain_Value_Definition: 
            Number for basalt and other volcanic-rock aquifers.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 999
          Enumerated_Domain_Value_Definition: 
            Number for areas that are not a principal aquifer.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: Aq_name
      Attribute_Definition: The aquifer unit name.  
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Unrepresentable_Domain: 
          There is no predefined set of official aquifer names.  The names used 
          in this data set are listed below.  There should be a direct
          correlation between the values of the rock_type and rock_name 
          attributes, and between the aq_name and aq_code attributes.  The 
          aq_names are as follows:
          >aq_code -- aq_name
          >0   -- null value, assigned to null polygon
          >101 -- Basin and Range aquifers
          >102 -- Rio Grande aquifer system
          >103 -- California Coastal Basin aquifers
          >104 -- Pacific Northwest basin-fill aquifers
          >105 -- Northern Rocky Mountains Intermontane Basins aquifer system
          >106 -- Central Valley aquifer system
          >107 -- High Plains aquifer
          >108 -- Pecos River Basin alluvial aquifer
          >109 -- Mississippi River Valley alluvial aquifer
          >110 -- Seymour aquifer
          >111 -- Surficial aquifer system
          >112 -- Puget-Willamette Lowland aquifer system
          >201 -- Coastal lowlands aquifer system
          >202 -- Texas coastal uplands aquifer system
          >203 -- Mississippi embayment aquifer system
          >204 -- Southeastern Coastal Plain aquifer system
          >205 -- Northern Atlantic Coastal Plain aquifer system
          >301 -- Colorado Plateaus aquifers
          >302 -- Denver Basin aquifer system
          >304 -- Lower Cretaceous aquifers
          >305 -- Rush Springs aquifer
          >306 -- Central Oklahoma aquifer
          >307 -- Ada-Vamoosa aquifer
          >308 -- Early Mesozoic basin aquifers
          >309 -- New York sandstone aquifers
          >310 -- Pennsylvanian aquifers
          >311 -- Mississippian aquifer of Michigan
          >312 -- Cambrian-Ordovician aquifer system
          >313 -- Jacobsville aquifer
          >314 -- Lower Tertiary aquifers
          >315 -- Upper Cretaceous aquifers
          >316 -- Wyoming Tertiary aquifers
          >401 -- Basin and Range carbonate-rock aquifers
          >402 -- Roswell Basin aquifer system
          >405 -- Ozark Plateaus aquifer system
          >406 -- Blaine aquifer
          >407 -- Arbuckle-Simpson aquifer
          >410 -- Silurian-Devonian aquifers
          >411 -- Ordovician aquifers
          >412 -- Upper carbonate aquifer
          >413 -- Floridan aquifer system
          >414 -- Biscayne aquifer
          >416 -- New York and New England carbonate-rock aquifers
          >417 -- Piedmont and Blue Ridge carbonate-rock aquifers
          >418 -- Castle Hayne aquifer
          >501 -- Edwards-Trinity aquifer system
          >502 -- Valley and Ridge aquifers
          >503 -- Mississippian aquifers
          >504 -- Paleozoic aquifers
          >505 -- Valley and Ridge carbonate-rock aquifers
          >601 -- Southern Nevada volcanic-rock aquifers
          >602 -- Northern California volcanic-rock aquifers
          >603 -- Pliocene and younger basaltic-rock aquifers
          >604 -- Miocene basaltic-rock aquifers
          >605 -- Volcanic-and sedimentary-rock aquifers
          >606 -- Snake River Plain aquifer system
          >607 -- Columbia Plateau aquifer system
          >999 -- Not a principal aquifer (field left blank).  Rocks that are 
          >       generally poorly permeable but locally may contain productive 
          >       aquifers.
    Attribute:
      Attribute_Label: Aq_code
      Attribute_Definition: 
        The code number relating to the aquifer unit name.  There should be a 
        direct correlation between the values of the rock_type and rock_name
        attributes, and between the aq_name and aq_code attributes.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0
          Range_Domain_Maximum: 999
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: 
        Aquifer boundaries and internal contacts (described by aquifrp.aat or 
        aquifrl025.dbf)
      Entity_Type_Definition: The limits of the aquifers shown.
      Entity_Type_Definition_Source: U.S. Geological Survey
    Attribute:
      Attribute_Label: Shape
      Attribute_Definition: The representation of the entity in the data.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: Polyline
          Enumerated_Domain_Value_Definition: 
            1-dimensional element that surrounds a 2-dimensional element.
          Enumerated_Domain_Value_Definition_Source: ESRI GIS software
    Attribute:
      Attribute_Label: FNODE# or Fnode_
      Attribute_Definition: Internal number of the from-node.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 5632
    Attribute:
      Attribute_Label: TNODE# or Tnode_
      Attribute_Definition: Internal number of the to-node.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 5632
    Attribute:
      Attribute_Label: LPOLY# or Lpoly_
      Attribute_Definition: 
        Internal number of the polygon to the left of the arc.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 4277
    Attribute:
      Attribute_Label: RPOLY# or Rpoly_
      Attribute_Definition: 
        Internal number of the polygon to the right of the arc.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 4267
    Attribute:
      Attribute_Label: Length
      Attribute_Definition: The length of the arc in coverage units.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 0.00159
          Range_Domain_Maximum: 16.14569
    Attribute:
      Attribute_Label: Aquifrp025# or Aquifrp025
      Attribute_Definition: Internal feature number.
      Attribute_Definition_Source: U.S. Geological Survey 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 6802
    Attribute:
      Attribute_Label: Aquifrp025-ID (Export format only)
      Attribute_Definition: User-assigned feature number.
      Attribute_Definition_Source: U.S. Geological Survey 
      Attribute_Domain_Values:
        Range_Domain:
          Range_Domain_Minimum: 1
          Range_Domain_Maximum: 6795
    Attribute:
      Attribute_Label: Lntype
      Attribute_Definition: The line category.
      Attribute_Definition_Source: U.S. Geological Survey
      Attribute_Domain_Values:
        Enumerated_Domain:
          Enumerated_Domain_Value: 1
          Enumerated_Domain_Value_Definition: 
            Coastline or international boundary.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey
        Enumerated_Domain:
          Enumerated_Domain_Value: 2
          Enumerated_Domain_Value_Definition: Interior aquifer contact line.
          Enumerated_Domain_Value_Definition_Source: U.S. Geological Survey

Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey, Water Resources Division
      Contact_Address:
        Address_Type: Mailing address
        Address: 12201 Sunrise Valley Drive
        City: Reston
        State_or_Province: VA
        Postal_Code: 20192
        Country: USA
      Contact_Voice_Telephone: 1-800-426-9000
  Distribution_Liability:  
    Although these data have been processed successfully on a computer system at 
    the U.S. Geological Survey, no warranty expressed or implied is made by the 
    U.S. Geological Survey regarding the utility of the data on any other 
    system, nor shall the act of distribution constitute any such warranty.
  Standard_Order_Process:
    Digital_Form: 
      Digital_Transfer_Information: 
        Format_Name: ARCE 
      Digital_Transfer_Option: 
        Online_Option: 
          Computer_Contact_Information: 
            Network_Address: 
              Network_Resource_Name: <http://nationalatlas.gov/atlasftp.html> 
      Digital_Transfer_Option: 
        Offline_Option: 
          Offline_Media: CD-ROM 
          Recording_Format: tar
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: ESRI Shapefile
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: <http://nationalatlas.gov/atlasftp.html>
      Digital_Transfer_Option:
        Offline_Option:
          Offline_Media: CD-ROM
          Recording_Format: tar
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: SDTS
      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name: <http://nationalatlas.gov/atlasftp.html>
      Digital_Transfer_Option:
        Offline_Option:
          Offline_Media: CD-ROM
          Recording_Format: tar

    Fees: 
      There is no charge for the online option.  For National Atlas files 
      ordered on CD-ROM there is a base price of $45.00 per disc, a handling fee 
      of $5.00, and a per-file charge based on file size.  The charge for files 
      less than 10 megabytes in size is $1.00.  The charge for files that range 
      in size from 10 to 150 megabytes is $7.50.  The charge for files of 150 
      megabytes or larger is $15.00.  The charge is $7.50 for the Principal 
      Aquifers of the 48 Contiguous United States data set.
    Ordering_Instructions: 
      To order files on CD-ROM, please see 
      <http://nationalatlas.gov/atlasftp.html#q12>.

Metadata_Reference_Information:
  Metadata_Date: 20011029
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
        Contact_Person: 
          Chief, Cartographic and Publications Program, Water Resources Division
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 505 Science Drive
        City: Madison
        State_or_Province: WI
        Postal_Code: 53711
        Country: USA
      Contact_Voice_Telephone: 608-238-9333
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Security_Information:
    Metadata_Security_Classification_System: None
    Metadata_Security_Classification: Unclassified
    Metadata_Security_Handling_Description: None