Geologic and structure maps of the Wallace 1°x2° quadrangle, Montana and Idaho: A digital database

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Frequently anticipated questions:

What does this data set describe?

Geologic and structure maps of the Wallace 1°x2° quadrangle, Montana and Idaho: A digital database
This dataset was digitized by the U.S. Geological Survey EROS Data Center and U.S. Geological Survey Spokane Field Office for input into an Arc/Info geographic information systsem (GIS) The digital geologic map database can be queried in many ways to produce a variety of derivative geologic maps.
This GIS consists of two major and Arc/Info datasets: one line and polygon file (wal250k) containing geologic contacts and structures (lines) and geologic map rock units (polygons), and one point file (wal250bc) containing breccia outcrops.
  1. How might this data set be cited?
    Harrison, J.E., Griggs, A.B., Wells, J.D., Kelley, W.N., and Derkey, P.D., 2000, Geologic and structure maps of the Wallace 1°x2° quadrangle, Montana and Idaho: A digital database: U.S. Geological Survey Miscellaneous Investigations Series Map I-1509-A, U.S. Geological Survey, Menlo Park CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -116.0
    East_Bounding_Coordinate: -114.0
    North_Bounding_Coordinate: 48.0
    South_Bounding_Coordinate: 47.0
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2000
    publication 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):
      • Point (5817)
      • String (14617)
      • GT-polygon composed of chains (5818)
    2. What coordinate system is used to represent geographic features?
      The map projection used is Transverse Mercator.
      Projection parameters:
      Scale_Factor_at_Central_Meridian: 1.00000
      Longitude_of_Central_Meridian: -115
      Latitude_of_Projection_Origin: 0
      False_Easting: 0.00000
      False_Northing: 0.00000
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.0001
      Ordinates (y-coordinates) are specified to the nearest 0.0001
      Planar coordinates are specified in Meters
      The horizontal datum used is North American Datum of 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?
    The "Geologic and structure maps of the Wallace 1°x2° quadrangle, Montana and Idaho: a digital database" report (wal250k.pdf) contains a detailed description of each attribute code and a reference to the associated map symbols on the map source materials. The database includes a geologic linework arc attribute table, wal250k.aat, that relates to the wal250k.con (contact look-up table), wal250k.st2 (structure look-up table), wal250k.lgu (linear geologic unit look-up table), and wal250k.ref (source reference look-up table) files; a rock unit polygon attribute table, wal250k.pat, that relates to the (rock unit look-up table) and wal250k.ref (source reference look-up table) files; and a breccia point attribute table, wal250bc.pat, that relates to the wal250bc.ref (source reference look-up table) files.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Harrison, J.E.
    • Griggs, A.B.
    • Wells, J.D.
    • Kelley, W.N.
    • Derkey, P.D.
  2. Who also contributed to the data set?
    Staff at EROS Data Center digitized the geologic map and prepared minimally attributed Arc/Info exchange-format files; R.J. Miller, R. Vandiver, M.C. Koenig (Eastern Washington University), and S.R. Munts (contractor) all participated in the initial edits of the dataset. William N. Kelley (contractor) completed the editing and attributing of arcs and polygons, and digitized the breccia point coverage (wal250bc).
  3. To whom should users address questions about the data?
    Pamela D. Derkey
    U.S. Geological Survey
    904 W. Riverside Ave., Rm. 202
    Spokane, WA

    1-509-368-3114 (voice)
    1-509-368-3199 (FAX)

Why was the data set created?

This dataset was developed to provide a geologic map GIS of the Wallace 1°x2° quadrangle for use in future spatial analysis by a variety of users.
This database is not meant to be used or displayed at any scale larger than 1:250,000 (e.g., 1:100,000 or 1:24,000)

How was the data set created?

  1. From what previous works were the data drawn?
    Harrison and others, 1986 (source 1 of 1)
    Harrison, J.E., Griggs, A.B., and Wells, J.D., 1986, Geology and structure maps of the Wallace 1°x2° quadrangle, Montana and Idaho: U.S. Geological Survey Miscellaneous Investigations Series Map Map I-1509-A, U.S. Geological Survey.

    Type_of_Source_Media: paper map
    Source_Scale_Denominator: 250,000
    Source_Contribution: This is the source for all the datasets
  2. How were the data generated, processed, and modified?
    Date: 1999 (process 1 of 2)
    Geologic map (Harrison and others, 1986) was digitized by USGS EROS Data Center and given minimal attributing. Dataset was edited and attributed by USGS Spokane Field Office staff and contractors.
    Date: 27-Jul-2000 (process 2 of 2)
    Creation of original metadata record Person who carried out this activity:
    U.S. Geological Survey
    Attn: Pamela D. Derkey
    904 W. Riverside Ave., Room 202
    Spokane, WA

    1-509-368-3114 (voice)
    1-509-368-3199 (FAX)
  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?
    Attribute accuracy was verified by manual comparison of the source with hard copy printouts and plots.
  2. How accurate are the geographic locations?
    Arcs and points are probably no more accurate than 58 meters based upon measurements taken by comparing a paper plot with an original plate from the Harrison and others (1986) report.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    All geologic units were captured from Harrison and others (1986) at a scale of 1:250,000.
  5. How consistent are the relationships among the observations, including topology?
    Polygon and chain-node topology present. Polygons intersecting the neatline are closed along the border. Segments making up the outer and inner boundaries of a polygon tie end-to-end to completely enclose the area. Line segments are a set of sequentially numbered coordinate pairs. No duplicate features exist nor duplicate points in a data string. Intersecting lines are separated into individual line segments at the point of intersection. Point data are represented by two sets of coordinate pairs, each with the same coordinate values. All nodes are represented by a single coordinate pair which indicates the beginning or end of a line segment. The neatline was generated by mathematically generating the four sides of the quadrangle, densifying the lines of latitude and projecting the file to Transverse projection.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
This digital database is not meant to be used or displayed at any scale larger than 1:250,000 (e.g., 1:100,000 or 1:24,000).
Any hardcopies utilizing these datasets shall clearly indicate their source. If users modify the data in any way they are obligated to describe the types of modifications they have performed on the hardcopy map. User specifically agrees not to misrepresent these datsets, nor to imply that changes they made were approved by the U.S. Geological Survey.
  1. Who distributes the data set? (Distributor 1 of 1)
    USGS Information Services
    Box 25286
    Denver Federal Center
    Denver, CO

    1-888-ASK-USGS (voice)
    303-202-4693 (FAX)
  2. What's the catalog number I need to order this data set? USGS Miscellaneous Investigations Series Map I-1509-A
  3. What legal disclaimers am I supposed to read?
    The U.S. Geological Survey (USGS) provides these geographic data "as is." The USGS makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. The USGS further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these data have been processed successfully on computers at the USGS, no warranty, expressed or implied, is made by the USGS regarding the use of these data on any other system, nor does the fact of distrubution constute or imply any such warranty.
    In no event shall the USGS have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic data or arising out of the delivery, installation, operation, or support by USGS.
    This digital geologic map GIS of the Wallace 1 x 2 degree quadrangle, Montana and Idaho, is not meant to be used or displayed at any scale larger than 1:250,000 (e.g., 1:100,000 or 1:24,000).
  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 05-Feb-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:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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