Preliminary geologic map of the Chugach National Forest special study area, Alaska

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Frequently anticipated questions:

What does this data set describe?

Preliminary geologic map of the Chugach National Forest special study area, Alaska
USGS Open-File Report 99-362 are digital files used to create the published paper map, USGS OFR 99-362. The 1:63,360 scale map shows the bedrock geology of a special study area within the Chugach National Forest, Alaska. Digital files include ARC/Info coverages in export format of geology, structural data, and annotation, and a PDF file of the Open-File Report.
USGS OFR 99-362 digital data consists of the following ARC/Info export files:
chuggeol.e00 - geology
chugstruct.e00 - point structure data
chuganno.e00 - geologic unit labels/annotation
  1. How might this data set be cited?
    Nelson, Steven W., Miller, Marti L., Haeussler, Peter J., Snee, Lawrence W., Phillips, Patti J., and Huber, Carol, 1999, Preliminary geologic map of the Chugach National Forest special study area, Alaska: U.S. Geological Survey Open-File Report 99-362.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 147.58
    East_Bounding_Coordinate: 147.0
    North_Bounding_Coordinate: 61.13
    South_Bounding_Coordinate: 60.85
  3. What does it look like? (PDF - Adobe portable document format)
    OFR99-362 with geologic map, text, tables (fossil ages, 40Ar/39Ar radiometric ages, major element geochemistry, Sr and Nd isotopic data), description of geologic units, correlation of map units, and references.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1999
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      UTM_Zone_Number: 6
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -147.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 200
      Ordinates (y-coordinates) are specified to the nearest 200
      Planar coordinates are specified in meters
  7. How does the data set describe geographic features?
    Characteristic of arcs in the arc attribute table of the geology coverage. (Source: USGS OFR 99-362)
    Arc-code is a positive integer value (3 3 I) item in the arc attribute table. Values range from 1-99. Arc-code describes the type of line feature. (Source: USGS OFR 99-362)
    1Stratigraphic or intrusive contact, location certain
    4Cross-section line
    7Shoreline or riverbank
    15Ice contact
    18Internal contact
    50Quartz vein, mineralized and unmineralized
    51Concealed contact
    52Concealed fault
    77Fault, location certain
    79Fault, location approximate
    93Lineament identified from air photos. Possible fault.
    99Bounding line of coverage
    Characteristic of the polygon features are coded in the pat, polygon attribute table. The pat consists of the following items: CLASS (4 5 B), and UNIT (geologic unit label). (Source: USGS OFR 99-362)
    Class is a positive integer value (4 5 B) item in the polygon attribute table. Values range from 0-128. There is a lookup table, chuggeol.lut, which contains the class, label, and color symbol number of each geologic unit. See USGS OFR 99-362 for full description of the geologic units. (Source: USGS OFR 99-362)
    7Q - Surficial deposits, undivided (Holocene)
    33Tosg - Orca Group shale or argillite (Lithofacies G) (Eocene and Paleocene)
    67Kvsbd - Valdez Group massive sandstone and rythmite (Lithofacies B and D) (Upper Cretaceous)
    69Kvsc - Valdez Group 'typical' turbidites (Lithofacies C) (Upper Cretaceous)
    70Tkvv - Volcanic and sedimentary rocks, undivided (Late Cretaceous and Tertiary)
    73Kvsb - Valdez Group massive sandstone (Lithofacies B) (Upper Cretaceous)
    85Tosbd - Orca Group massive sandstone and rythmite (Lithofacies B) (Eocene and Paleocene)
    86Tosb - Orca Group massive sandstone (Lithofacies B) (Eocene and Paleocene)
    88Tosf - Orca Group chaotic deposits (Lithofacies F) (Eocene and Paleocene)
    93Tosc - Orca Group 'typical' turbidites (Lithofacies C) (Eocene and Paleocene)
    96Tosa - Orca Group conglomerate (Lithofacies A) (Eocene and Paleocene)
    97Tosd - Orca Group rythmite (Lithofacies D) (Eocene and Paleocene)
    107Tf - Felsite dikes (Tertiary)
    112Tgd - Gabbro and diorite of Miners Bay (Oligocene)
    119Tg - Leucocratic granite (Oligocene)
    120Tosv - Orca Group volcaniclastic rocks (Eocene and Paleocene)
    123Top - Orca Group pillow basalt (Eocene and Paleocene)
    126Tod - Orca Group sheeted dikes (Eocene and Paleocene)
    Geologic unit label (Source: USGS 99-362)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Nelson, Steven W.
    • Miller, Marti L.
    • Haeussler, Peter J.
    • Snee, Lawrence W.
    • Phillips, Patti J.
    • Huber, Carol
  2. Who also contributed to the data set?
    Patti J. Phillips, Kelly M. Brunt (Raytheon contractor)
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Peter J. Haeussler
    4200 University Drive
    Anchorage, AK

    907-561-1181 (voice)

Why was the data set created?

Digital representation of geologic mapping of the Chugach National Forest Special Study Area is to facilitate the presentation and analysis of earth-science data. Digital maps can be displayed at any scale or projection, however the geological data in this coverage is not intended for use at a scale larger than 1:63,360.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 1999 (process 1 of 2)
    Linework was captured by hand digitizing from a stable base line drawing. The digital linework was edited and attributed using ARC/Info. The coverage was built for polygon topology, and had labels created and attributed. For purpose of distribution, the coverage has been converted to an interchange format file using the ARC/Info export command.
    Date: 27-Sep-1999 (process 2 of 2)
    Creation of original metadata record Person who carried out this activity:
    U.S. Geological Survey
    Attn: Nora Shew
    4200 University Drive
    Anchorage, AK

    907-561-1181 (voice)
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The linework was captured by hand digitizing from hand-drawn 1:63,360-scale stable base mylar maps in good condition. Vector and polygon attributes were obtained from field maps and compilations. The digital data has been visually checked and the geologic map has undergone technical review.
  2. How accurate are the geographic locations?
    Users of this digital geologic map should respect the intentions of the original mappers and the limitations of the map. This 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.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    The digital data files are the geospatial files used to created the geologic map. They do not include the tables, text or figures shown in the Open-File Report.
  5. How consistent are the relationships among the observations, including topology?
    The geology data set, chuggeol, is a network coverage containing arcs and polygons. Each polygon has a coded attribute designating the mapped geologic unit. 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.)
    The data set, chugstruct, is a point coverage containing annotation. This coverage displays the strike and dip measurements of beds and folds.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints: None
  1. Who distributes the data set? (Distributor 1 of 1)
    USGS Information Services
    Box 25286
    Denver Federal Center
    Denver, Co

    303-202-4200 or 1-888-ASK-USGS (voice)
  2. What's the catalog number I need to order this data set? USGS OFR 99-362 (digital)
  3. What legal disclaimers am I supposed to read?
    Although this data has 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, software, or related materials.
  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 10-Jun-2016
Metadata author:
Peter N Schweitzer
USGS Midwest Area
Collection manager, USGS Geoscience Data Clearinghouse,
Mail Stop 954
12201 Sunrise Valley Dr
Reston, VA

703-648-6533 (voice)
703-648-6252 (FAX)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

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