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

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. Where did the data come from?
  2. What changes have been made?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

Title:

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

Abstract:

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.

Supplemental_Information:

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

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 OFR 99-362.

Online Links:

<https://pubs.usgs.gov/of/1999/0362/>

West_Bounding_Coordinate: 147.58

East_Bounding_Coordinate: 147.0

North_Bounding_Coordinate: 61.13

South_Bounding_Coordinate: 60.85

of99-362.pdf (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.

Calendar_Date: 1999

Currentness_Reference: publication date

Geospatial_Data_Presentation_Form: vector digital data

This is a Vector data set.

Grid_Coordinate_System_Name: Universal Transverse Mercator

Universal_Transverse_Mercator:

UTM_Zone_Number: 6

Transverse_Mercator:

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

arcs

Characteristic of arcs in the arc attribute table of the geology coverage. (Source: USGS OFR 99-362)

arc-code

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)

polygons

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

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)

unit

Geologic unit label (Source: USGS 99-362)

Text field

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
   c/o Peter J. Haeussler
   Geologist
   4200 University Drive
   Anchorage, AK 99508-4667
   USA
   

   907-561-1181 (voice)
   pheuslr@usgs.gov
   

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. Where did the data come from?
2. What changes have been made?

   Date: 1999 (change 1 of 1)

   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.

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 I 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 80225-0046
   USA
   

   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?

   Data format:	ARCE
   Network links:	<http://wrgis.wr.usgs.gov/open-file/of99-362>

Who wrote the metadata?

Dates:

Last modified: 27-Sep-1999

Metadata author:

U.S. Geological Survey
c/o Nora Shew
4200 University Drive
Anchorage, AK 99508-4667
USA

907-561-1181 (voice)
nshew@usgs.gov

Metadata standard:

FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)