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Isopachs of total net coal in A-D coal zones, Yampa Coal Field

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. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  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?

1. How should this data set be cited?

   U.S. Geological Survey, Central Energy Resources Team, Johnson, E.A., Roberts, L.N.R., and Brownfield, M.E., 2000, Isopachs of total net coal in A-D coal zones, Yampa Coal Field: U.S. Geological Survey, Denver, CO USA.

   Online Links:

   • <http://energy.cr.usgs.gov/coal/nca/cpgis.htm>

   Other_Citation_Details:

   In subdir 500k (defines appropriate maximum scale for data use)
   chap. P, Geology and resource assessment of the middle and upper coal groups in the Yampa coal field, northwestern Colorado

   This is part of the following larger work.

   Kirschbaum, M.A., Roberts, L.N.R., and Biewick, L.R.H., 2000, Geologic Assessment of Coal in the Colorado Plateau: U.S. Geological Survey Professional Paper 1625-B, U.S. Geological Survey, Denver, CO.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -107.8897

   East_Bounding_Coordinate: -106.9577

   North_Bounding_Coordinate: 40.6013

   South_Bounding_Coordinate: 40.2496

3. What does it look like?

4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 1997

   Ending_Date: 1998

   Currentness_Reference: Processing Date

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: map

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. It contains the following vector data types (SDTS terminology):

      • GT-polygon composed of chains (22)

   2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest .0001. Longitudes are given to the nearest .0001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
      

7. How does the data set describe geographic features?

   yam*_thk.dbf

   Shapefile Attribute Table (Source: None)

   Area

   Area of polygon (Source: Software computed)

   Range of values
   Minimum:	0.000
   Maximum:	0.087

   Perimeter

   Perimeter of polygon (Source: Software computed)

   Range of values
   Minimum:	0.027
   Maximum:	3.030

   Depth

   Net coal thickness in beds greater than or equal to 1.2 ft.

   Range of values
   Minimum:	10.00
   Maximum:	90.00

   Depth2

   Net coal thickness in beds greater than or equal to 1.2 ft.

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • U.S. Geological Survey, Central Energy Resources Team
   • Johnson, E.A.
   • Roberts, L.N.R.
   • Brownfield, M.E.

2. Who also contributed to the data set?

3. To whom should users address questions about the data?
   U.S. Geological Survey, Central Energy
   c/o Johnson, E.A.
   PO Box 25046 MS 939 Denver Federal Center
   Denver, CO 80225
   USA
   

   303.236.4857 (voice)
   

Why was the data set created?

The Nation's coal resources are being reassessed by the USGS. This assessment identifies and characterizes the coal beds and coal zones that will provide the bulk of the nation's coal-derived energy during the next century. This assessment is different from previous large-scale USGS assessments because files and databases are being stored in a digital format and are being analyzed using a Geographic Information System (GIS).

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: 1998 (process 1 of 1)

   Initial queries of the Stratifact database were made for only those records that contain data on each of the four coal zones resulting in four separate files (subsets) of the database. These were input files for a parting/split program. This program, written at the USGS, determines whether a rock unit between two coal units is a parting in a coal bed or if the rock unit splits two separate coal beds as defined in (Wood and others, 1983, p. 36). Coal units are combined to form a single bed if the thickness of rock between them is thinner than the coal on either side. If the rock is thinner it is considered to be a parting and if it is thicker it is considered to be a split. After the program calculates the thickness of coal in each coal bed it determines if the coal beds are greater than the minimum thickness requirement as a resource. For coals of bituminous rank, this minimum thickness is 1.2 ft. (Wood and others, 1983, p.34). Coals in the Yampa coal area are bituminous in rank. The program goes through another process where it sums coal bed thickness of only the coal beds that are greater than or equal to the minimum thickness (1.2'). The program outputs a single line of data for each location with net coal thickness and x, y location parameters. The data output from this program also contains a column designating the number of coal beds that were added to arrive at the net coal thickness. Output files from the parting/split program were introduced into EarthVision (EV) as scattered data files and projected into Lambert Conformal Conic projection. Locations with a net coal thickness value of zero were appended to the scattered data file (applicable only to the B and C coal zones) to control extrapolation during gridding. These scattered data files were then gridded in EV using the 'minimum tension grid' option. The isopach maps for each coal zone were plotted in EV with a contour interval that best-depicts the coal thickness distribution with an added contour line for 1.2 ft, if applicable. The contour lines were saved in contour output files. The contour output files were converted to files in 'arc generate' format using ISMARC and then converted to ARC/INFO polygon coverages using an Arc Macro Language program from the Illinois State Geological Survey. The coverages were converted to shapefiles using ArcView.

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?

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?

   Complete

5. How consistent are the relationships among the observations, including topology?

   Polygon topology present.

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: Appropriate maximum scale for data use is 500k.

1. Who distributes the data set? (Distributor 1 of 1)
   U.S. Geological Survey, Central Energy
   PO Box 25046 MS 939 Denver Federal Center
   Denver, CO 80225
   USA
   

   303.236.4608 (voice)
   

2. What's the catalog number I need to order this data set?

   Shapefile and ARC/INFO coverage

3. What legal disclaimers am I supposed to read?

   Any use of trade, product, or company names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. 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 USGS regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. This data is not a legal document and is not intended to be used as such.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	ARC/INFO coverage, export file and shapefile (version ARC/INFO 7.0.4, ArcView 2.1)
     Network links:	<http://energy.cr.usgs.gov/coal/nca/cpgis.htm>
     Media you can order:	CD-ROM (format ISO 9660)

   • Cost to order the data: none

5. What hardware or software do I need in order to use the data set?

   need ARC/INFO 7.0.4 or greater and/or ArcView 2.1 or greater and/or ArcExplorer (which can be downloaded free from <URL:http://www.esri.com>) and/or other software that can read ARC/INFO coverages, ARC/INFO export files, and/or shapefiles
   

Who wrote the metadata?

Dates:

Last modified: 03-Feb-1999

Metadata author:

U.S. Geological Survey, Central Energy
PO Box 25046 MS 939 Denver Federal Center
Denver, CO 80225
USA

303.236.4608 (voice)

Metadata standard:

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