Identification_Information:
  Citation:
    Citation_Information:
      Originator: James R. Riehle
      Originator: Frederic H. Wilson
      Originator: Nora Shew
      Originator: Willis H. White
      Publication_Date: 1999
      Title:
        Geologic map of Unga Island and the northwestern part of
        Popof Island, Alaska
      Geospatial_Data_Presentation_Form: map
      Series_Information:
        Series_Name: U.S. Geological Survey Open-File Report
        Issue_Identification: 99-136
      Other_Citation_Details:
        Riehle, J.R., Wilson, F.H., Shew, Nora, White, W.H., 1999,
        Geologic map of Unga Island and the northwestern part of
        Popof Island, Alaska:  U.S. Geological Survey Open-File
        Report 99-136, scale 1:63,360.
      Larger_Work_Citation:
        Citation_Information:
          Originator: Riehle, J.R. (ed.)
          Publication_Date: 1999
          Title:
            Geological and geophysical setting of the gold-silver
            vein systems of Unga Island, southwestern Alaska
          Geospatial_Data_Presentation_Form: map
          Series_Information:
            Series_Name: U.S. Geological Survey Open-File Report
            Issue_Identification: 99-136
          Other_Citation_Details:
            Riehle, J.R., ed., Geological and geophysical setting
            of the gold-silver vein systems of Unga Island,
            southwestern Alaska:  U.S. Geological Survey Open-File
            Report 99-136, CD-ROM.

            The CD-ROM contains seven chapters, including shaded-
            relief images of Unga Island showing topographic lineaments
            that are the physiographic expression of mineralized
            faults, geologic map, airborne magnetic and resistivity
            data, rock- and stream- sediment geochemical data, and a
            statistical analysis of the probable gold-deposit type.
  Description:
    Abstract:
      This dataset is a geologic map units created as annotated
      polygons of an ARC/Info coverage.  The geologic polygons
      together with five other coverages compose a geologic
      map at 1:63,360 scale.  Both the plotfile and a graphic
      version of the map as a viewable image are presented on
      the CD-ROM publication.  The other coverages, which
      are not described in separate metadata files, are as
      follows:  topographic contours as a line coverage,
      faults and physographic lineaments as a line coverage,
      areas of alteration as a polygon coverage, bedding
      orientations (strike and dips) as a point coverage, and
      symbols such as mines and drill holes as a point coverage.

    Purpose:
      This geologic map was developed as part of a study of the
      nature and origin of the gold-silver vein systems on
      Unga Island.  Previously published mapping was at
      1:250,000 scale, too small a scale to support the vein
      study.
    Supplemental_Information:
      All six ARC/Info coverages relating to the geologic
      map are available on the CD-ROM as export files.  The
      airborne magnetic and resistivity survey datasets are
      also provided as ascii line-data files and as grids; the
      geophysical contractor's report and image files from the
      interpretive geophysics chapter of the CD-ROM are
      included as well.  The geophysical survey extends over
      only the southeastern one-sixth of Unga Island,
      whereas the geologic map coverages include the entire
      island.  A USGS-formatted DEM (30-m cellsize) of the
      study area is provided, which is the basis of the
      shaded-relief images and the topographic line coverage.
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 1999
    Currentness_Reference: publication date
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: Unknown
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -160.89
      East_Bounding_Coordinate: -160.27
      North_Bounding_Coordinate: 55.43
      South_Bounding_Coordinate: 55.11
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: None
      Theme_Keyword: geology
      Theme_Keyword: bedrock
      Theme_Keyword: gold
      Theme_Keyword: volcanic
    Place:
      Place_Keyword_Thesaurus: None
      Place_Keyword: Unga Island
      Place_Keyword: Popof Island
      Place_Keyword: Shumagin Islands
      Place_Keyword: Alaska
  Access_Constraints: None
  Use_Constraints: None
  Point_of_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization:
          U.S. Geological Survey
          Mineral Resource Program - Alaska Section
        Contact_Person: James R. Riehle
      Contact_Position: Geologist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 4200 University Drive
        City: Anchorage
        State_or_Province: AK
        Postal_Code: 99508-4667
        Country: USA
      Contact_Voice_Telephone: 907-561-1181
      Contact_Electronic_Mail_Address: jriehle@usgs.gov
  Browse_Graphic:
    Browse_Graphic_File_Name: *** add name of file to be on CD
    Browse_Graphic_File_Description: *** enter browse graphic description
    Browse_Graphic_File_Type: *** enter browse graphic file name
  Data_Set_Credit: J.R. Riehle, and J.D. Hall, Raytheon STX Contractor
  Native_Data_Set_Environment:
    This coverage was created using ESRI ARC/Info version 7
    on a Unix platform
Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report:
      This geologic map was compiled from hand-drawn field
      maps on 1:63,360 scale paper topographic maps.  Polygons
      were hand-digitized by visual reference to topographic
      contours on a back-coverage.  DEM and derivative products
      like shaded-relief images and topographic line coverage
      created by scanning 1:63,360 paper topographic maps at
      300 dpi, importing the scanned images as TIF file,
      registering them to Albers coordinates, rectifying,
      and converting to a vector coverage.  Contours were then
      edited and cleaned by removing extraneous lines such as
      cultural features and were assigned the appropriate
      elevations to the item "elev".  Lastly, the coverage
      was converted to a lattice and the lattice to a DEM.
      (Assistance in scanning and importing the topographic
      maps from Bo Wilmer, ECO Cooperative Agreement
      1434-96-A-01453.)
  Logical_Consistency_Report:
    This coverage is a net coverage containing arcs and
    polygons.  Each polygon has a class attribute classifying
    bedrock, surficial deposit, or water body.  Faults and
    stratigraphic contacts are represented as arcs.  When a
    fault is also a stratigraphic contact, only a single arc
    is present.  Dangling arcs may be present (faults, dikes,
    etc.)
  Completeness_Report:
    In addition to this polygon coverage of geologic units,
    the geologic map is built from (i) a polygon coverage of
    alteration areas, (ii) a line coverage of structural
    fold axes, physiographic lineaments, faults, dikes, and
    veins, (iii) a point coverage of strike and dip
    measurements, (iv) a point coverage of annotation symbols
    such as mines, drill holes, and exploration trenches, and
    (v) a line coverage of topographic elevation contours.
    The graphics plotfile includes a considerable amount of
    text and collar information, such as abbreviated
    descriptions of geologic units, a correlation chart that
    shows geologic ages of the units, explanation of map
    symbols, scale bar, and latitude and longitude ticmarks.
    The Open-File publication also includes descriptive and
    interpretive text and a structural cross-section
    through the middle of the map area.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report:
        Users of this digital geologic map should respect the
        intentions of the original mappers and the limitations
        of the map.  The Unga geologic map is intended to be
        used at a scale of 1:63,360; it is not intended to be
        used at a more detailed scale.
  Lineage:
    Process_Step:
      Process_Description:
        Geologic map compiled from hand-drawn field maps on
        1:63,360 scale paper topographic maps, then hand
        digitized by visual reference to topographic contours
        on a back coverage.  The linework was edited and cleaned
        in ARC/Info, then attributed for labels and built for
        polygon topology.  The CD/ROM publication includes both
        the graphics plotfile and export files of each of the
        constituent coverages created using the ARC/Info
        "export" command.
      Process_Date: 1998
      Process_Contact:
        Contact_Information:
          Contact_Organization_Primary:
            Contact_Organization: U.S. Geological Survey
            Contact_Person: James R. Riehle
          Contact_Position: Geologist
          Contact_Address:
            Address_Type: mailing and physical address
            Address: 4200 University Drive
            City: Anchorage
            State_or_Province: AK
            Postal_Code: 99508-4667
            Country: USA
          Contact_Voice_Telephone: 907-561-1181
          Contact_Electronic_Mail_Address: jriehle@usgs.gov
Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Vector
Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Planar:
      Grid_Coordinate_System:
        Grid_Coordinate_System_Name: Universal Transverse Mercator
        Universal_Transverse_Mercator:
          UTM_Zone_Number: 4
          Transverse_Mercator:
            Scale_Factor_at_Central_Meridian: 0.9996
            Longitude_of_Central_Meridian: -159
            Latitude_of_Projection_Origin: 0.0
            False_Easting: 500000
            False_Northing: 0.0
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: coordinate pair
        Coordinate_Representation:
          Abscissa_Resolution: 150.
          Ordinate_Resolution: 150.
        Planar_Distance_Units: meters
Entity_and_Attribute_Information:
  Detailed_Description:
    Entity_Type:
      Entity_Type_Label: arc-code
      Entity_Type_Definition:
        Arc-code is a positive integer value (3 3 I) item in the
        arc attribute table. Values range from 1-6.  It identifies
        the line type.  The values in this data set are:

        1   stratigraphic contact, certain; or shoreline
        2   annotation leaders
        6   stratigraphic contact, inferred or approximately
        located
      Entity_Type_Definition_Source: Riehle and others, 1999
    Entity_Type:
      Entity_Type_Label: class
      Entity_Type_Definition:
        Class is a positive integer value (4 5 B) item in the
        polygon attribute table.  Values range from 0-8000.
        It identifies the geologic unit (rock type and geologic
        age).  A lookup table, unga.lut, located in the INFO
        directory keys the class value with the label of the
        geologic unit.  The values in this data set are:

        0    unmapped areas
        100  Qs - Colluvium, alluvium and beach deposits (Holocene)
        110  Qls - Landslide and talus deposits (Holocene)
        125  Qm - Glacial deposits (Pleistocene)
        200  Tu - Unga Fm. (Miocene and Oligocene)
        210  Tpu - Undifferentiated Popof volcanics (late
        Eocene to Oligocene).  Subdivided into: class 220-250.
        220  Tpdu - Domes, undifferentiated (Oligocene)
        221  Tpda -  Andesitic domes
        222  Tpdb -  Basaltic andesite domes
        223  Tpdd -  Dacitic domes
        224  Tpdr -  Rhyolitic domes
        230  Tpth -  Hornblende tuff (Oligocene)
        240  Tps -  Volcaniclastic rocks (late Eocene to
        Oligocene)
        250  Tptb - Biotite tuff (Oligocene)
        300  Tmv - Volcanic rocks (Miocene)
        310  Tmb - Basalt flows (Miocene)
        400  Ts - Stepovak Fm (Eocene and Oligocene)
        410  Tpz - Lavas of Zachary Bay (Tertiary)
        500  s - areas of thorough replacement by silica
        8000  water
      Entity_Type_Definition_Source: Riehle and others, 1999
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: USGS Information Services
      Contact_Address:
        Address_Type: mailing address
        Address:
          Box 25286
          Denver Federal Center
        City: Denver
        State_or_Province: CO
        Postal_Code: 80225-0046
        Country: USA
      Contact_Voice_Telephone: 303-202-4200 or 1-888-ASK-USGS
      Contact_Facsimile_Telephone: 303-202-4695
  Resource_Description:
    This geologic map coverage is chapter 2 in U.S.G.S.
    Open-File Report 99-136, CD-ROM publication.
  Distribution_Liability:
    This Compact Disc-Read Only Memory (CD-ROM) publication
    was prepared by an agency of the United States Government.
    Neither the United States Government nor any agency
    thereof, nor any of their emmployees, makes any warranty,
    expressed or implied, or assumes any legal liability
    or responsibility for the accuracy, completeness, or
    usefulness of any information, apparatus, product, or
    process disclosed in this report, or represents that its
    used would not infringe privately owned rights.
    Reference therin to any specific commercial product,
    process, or service by trade name, trademark, manufacturer,
    or otherwise does not necessarily constitute or imply its
    endorsement, recommendation, or favoring by the United
    States Government or any agency thereof.

    Although all data and software 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 and (or) the functioning
    of the software.  The act of distribution shall not
    constitute any such warranty, and no responsibility
    is assumed by the USGS in the use of this data,
    software, or related materials.
Metadata_Reference_Information:
  Metadata_Date: 19990308
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: USGS Mineral Resources Program - Alaska Section
        Contact_Person: Nora B. Shew
      Contact_Position: Geologist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 4200 University Drive
        City: Anchorage
        State_or_Province: AK
        Postal_Code: 99508-4667
        Country: USA
      Contact_Voice_Telephone: 907-561-1181
      Contact_Electronic_Mail_Address: nshew@usgs.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: June 8, 1994