Snake/Salt Basin Plan

Land Survey System - Section, Township, and Range

Metadata also available as

Frequently-anticipated questions:

What does this data set describe?
    Title: trsec_ssdd27
    Abstract:
    This dataset represents a 1:100,000 scale Public Land Survey System layer for Wyoming. It was digitized from 57 different paper copies of BLM Surface Management Status series maps for Wyoming. (One map was from Idaho but covered a small section of Wyoming.)

  1. How should this data set be cited?

    Wyoming Water Resources Center, 1994, trsec_ssdd27: University of Wyoming Spatial Data and Visualization Center, Laramie, Wyoming.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -111.048996
    East_Bounding_Coordinate: -109.763680
    North_Bounding_Coordinate: 44.490398
    South_Bounding_Coordinate: 42.484280

  3. What does it look like?

    <URL:http://www.sdvc.uwyo.edu/images/plss.gif>plss.gif (gif)
    example of plss sections for northwest Wyoming

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

    Calendar_Date: REQUIRED: The year (and optionally month, or month and day) for which the data set corresponds to the ground.
    Currentness_Reference: Publication date of sources

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

      • G-polygon (5467)
      • String (204132)
      • GT-polygon composed of chains (97952)

    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 0.000000. Longitudes are given to the nearest 0.000000. Latitude and longitude values are specified in Decimal degrees.

      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 6378206.400000.
      The flattening of the ellipsoid used is 1/294.978698.

  7. How does the data set describe geographic features?

    trsec_ssdd27
    Contains attributes for all polygons (Source: source maps)

    FID
    Internal feature number. (Source: ESRI)

    Range of values
    Minimum:T12N (T3S, Wind River Indian Reservation)
    Maximum:T58N (T9N, Wind River Indian Reservation)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Range of values
    Minimum:R60W (R6E, Wind River Indian Reservation)
    Maximum:R121W (R6W, Wind River Indian Reservation)

    Coordinates defining the features.

    MERIDIAN
    PLSS Section (Source: source maps)

    Range of values
    Minimum:1
    Maximum:36 (99, no designation)

    SECTION

    TOWNSHIP

    RANGE

    TDISPLAY

    RDISPLAY

    TRDISPLAY

    SOURCE

    SCALE

    CREATED

    MODIFIED

    TECH

    SUFFIX

    WY_PLSS.MAP
    Contains names/dates of source maps (Source: source maps)

    map
    name of source map (Source: source maps)

    Formal codeset
    Codeset Name:USGS 1:100,000-scale quadrangle name
    Codeset Source:USGS series

    date
    date of source map publication (Source: source maps)

    Range of values
    Minimum:1974
    Maximum:1991

    Entity_and_Attribute_Overview:
    All meaningful attributes are included in the WY_PLSS.PAT file. Only polygon attributes were created for the layer. All coding was done within the fields TOWNSHIP, RANGE, and SECTION. TOWNSHIP and RANGE are character fields containing codes like "T21N" while SECTION is an integer field containing a number from 1 - 36 or 99 where no data was available. In some instances half-township codes were used (T21.5N) for small fractions of townships at junctions between two different surveys. WY_PLSS.MAP is a file associated with this dataset which lists all the names and publication dates of the source maps used in creating this digital spatial dataset.
    Entity_and_Attribute_Detail_Citation: none

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    U.S. Bureau of Land Management (source maps), Chris Arneson (digitization)

  3. To whom should users address questions about the data?

    Data Manager
    Spatial Data and Visualization Center
    Box 4008 University Station
    Laramie, Wyoming 82071
    USA

    307-766-2735 (voice)
    n/a

    Hours_of_Service: 8 AM to 5 PM MST

Why was the data set created?
This dataset was created for the purposes of identifying township/range section descriptions for areas in Wyoming within a spatial query/analysis context using GIS.

How was the data set created?
  1. From what previous works were the data drawn?

    source maps (source 1 of 2)
    Bureau of Land Management, 1974-1991, BLM Surface Management Status Maps for Wyoming.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 100000
    Source_Contribution: source maps for digitization

    landownership map (source 2 of 2)
    Analysis, Wyoming Gap , 1996, Landownership for Wyoming.

    Type_of_Source_Media: digital map
    Source_Scale_Denominator: 100000
    Source_Contribution: source maps for digitization

  2. How were the data generated, processed, and modified?

    Date: 1993 (process 1 of 3)
    The source maps for this dataset were digitized using ARC/INFO Version 6.1.2 on a Sun Microsystems IPC workstation. Each map was first securely taped to the digitizer and registered to a master tic coverage created for the state using 15 tics per map. The master coverage contained 492 tics keyed into ARC/INFO with lat/long coordinates. This tic coverage was then projected to both UTM zone 12 and UTM zone 13 to cover both halves of Wyoming. When registering, an RMS error of 0.006 inches was set as our highest allowable error. Because of the quality of two of the source maps (Baggs and Chugwater), however, an RMS error of 0.007 inches had to be accepted for these two maps. The maps were then digitized in a "spaghetti" fashion and cleaned with the smallest fuzzy tolerance that ARC/INFO would allow. All dangle and sliver errors were then removed and the coverage was attributed. Each coverage was then reviewed (linework and attributes) and temporarily archived. When all 57 quads were digitized and reviewed the coverages were EDGEMATCHed to one another. Because the source maps were in two different projections only half of the state was edgematched and joined at a time. When these halves were finished, they were then joined to one another in a common projection. When one coverage was edgematched to another, a maximum adjustment distance was set to approximately one mile on the ground (or slightly more than one cm on the map). The coverages were then joined and adjoining lines removed. The coverage was then once again reviewed. To maintain consistency in boundaries throughout the WWRC GIS Lab's archive, the Wyoming state boundary for this set was taken from the landownership layer previously digitized by the Wyoming Gap Analysis Project in 1992. Because similar data automation techniques and review were used on both datasets the accuracy of the Wyoming state boundary should be viewed as the same accuracy as this dataset.

    Data sources used in this process:

    • source maps, landownership map

    Date: May-1997 (process 2 of 3)
    Errors were discovered in some of the attributes of the first version of the PLSS coverage. Attributes for RANGE, R95N were changed to R95W; attributes R108 were changed to R108W to be consistent with other labelling conventions. It should also be noted that some TOWNSHIP attributes are labeled as T25.5 which is correct, not an error. The coverage with these attribute changes is refered to as Version or Edition 2.

    Data sources used in this process:

    • none

    (process 3 of 3)
    Metadata imported.

    Data sources used in this process:

    • C:\DOCUME~1\decook\LOCALS~1\Temp\xml5A.tmp

  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?

    Each map once digitized was plotted on semi-translucent paper and overlayed with the original on a light-table. Any inconsistencies in linework or attributing was noted on the map and "checked off" as the needed changes were completed. (Lab standards similar to National Mapping Standards were strictly followed. For example, lab standards required that any linework deviating from the original map enough for "white space" to exist between the edit plot and the source map be documented and fixed. Step one was then performed again until no more errors were found.) Once all digitized maps were joined into one coverage several "dissolve" processes were performed to look for any inconsistencies in attributing. Dissolves were performed on both TOWNSHIP and RANGE. Searches were also made on the coverage for unattributed slivers and for polygons less than 10 acres that might have been errors.

  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?

    The township/range section attributes are complete for all polygons in in Wyoming, except where there were no township/range/section designations on the source maps, in which case these polygons were labelled with a code of 99. All lot and tract descriptions were avoided.

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

    All polygons are closed and adjacent polygons do not have identical attributes. Each polygon has one and only one attribute.

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:
Data was created from 1:100,000 scale paper copy maps. It must be assumed that some "paper stretch" or distortion is included in the data and that the data is only as accurate as the paper maps it was produced from. The source maps were from various years and in various physical conditions. Some were newer maps in excellent shape, while others (Chugwater) were older (1974) and folded. In areas where surveys have not been done a code of 99 was used. All lot and tract descriptions were avoided. This data should never be used at a scale greater than 1:100,000 and not in situations other than regional or small-scale analysis is required.

  1. Who distributes the data set? (Distributor 1 of 1)

    Data Manager
    Spatial Data and Visualization Center
    Box 4008 University Station
    Laramie, Wyoming 82071
    USA

    307-766-2735 (voice)
    n/a

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

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    The distributor shall not be held liable for improper or incorrect use of this data, based on the description of appropriate/inappropriate used described in this metadata document. It is strongly recommended that this data is directly acquired from the distributor described above and not indirectly through other sources which may have changed the data in some way. This data was developed and is meant to be used at the 1:100,000-scale (or smaller scale) for the purpose of identifying township/range sections in Wyoming. The distributor makes no claims for the data's suitability for other purposes.

  4. How can I download or order the data?

Who wrote the metadata?
Dates:
Last modified: 14-May-2004

Metadata author:
Margo Berendsen
Box 4008 University Station
Laramie, Wyoming 82071
USA

307-766-2751 (voice)
meh@uwyo.edu

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

Metadata extensions used:

Generated by mp version 2.7.33 on Fri May 14 13:53:03 2004