Wyoming Surficial Geology

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Frequently-anticipated questions:

What does this data set describe?
    Title: Wyoming Surficial Geology
    Abstract:
    This dataset represents surficial geology of Wyoming at 1:500,000-scale. The layer contains 577 separate surficial feature (landforms) and deposit descriptions present on the surface in the state. Compiled from aerial photography and existing maps this layer represents the first comprehensive surficial geology map of Wyoming.

  1. How should this data set be cited?

    James C. Case, Christopher S. Arneson, and Laura L. Hallbe, 1998, Wyoming Surficial Geology: Spatial Data and Visualization Center, Laramie, Wyoming.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -111.26477012
    East_Bounding_Coordinate: -103.83670034
    North_Bounding_Coordinate: 44.99903411
    South_Bounding_Coordinate: 40.94837176

  3. What does it look like?

    <URL:http://www.sdvc.uwyo.edu/images/surfgeol.gif> (gif)
    surficial geology

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

    Calendar_Date: 1998
    Currentness_Reference: 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. It contains the following vector data types (SDTS terminology):

      • GT-polygon composed of chains (16609)

    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 .001. Longitudes are given to the nearest .001. Latitude and longitude values are specified in Decimal Degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.

  7. How does the data set describe geographic features?

    surfgeol_ssdd27

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    AREA

    PERIMETER

    SURFGEOL_

    SURFGEOL_I

    SG_UNIT

    RECLASS

    DISPLAY

    Entity_and_Attribute_Overview:
    The classification scheme has two phases, with the first phase being a simple classification of single units, such as alluvium (a), colluvium (c), eolian (e), bedrock (R), and grus (u). The complete single-element classification is as follows: A old alluvial plain - a broad, relatively flat deposit formed by the regional erosion of coalescing alluvial and associated alluvial deposits. a alluvium - stream and river deposits b bench - a strip of relatively level earth or rock, raised and capped with gravel. b/m bench and/or mesa (could not be determined from aerial photos) c colluvium - loose and incoherent deposits, usually at the foot of a cliff or on the surface of a slope and there chiefly by gravity. d dissected e eolian deposits - wind blown deposits, includes sand, silt, and clay f alluvial fan deposits - a fan shaped deposit made by a stream or a debris flow where they have run out onto a level plain. G glaciated bedrock - bedrock that has been scoured and carved out by glacial action. g glacial deposits - deposits that have been formed through glacial action, such as till and moraine. h hot spring deposit - travertine and silaceous sinter deposits. i includes other surficial deposits (25 element classification) K Karst - a type of topology formed over limestone, dolomite, gypsum, or other salts by dissolving or solution, and that is characterized by closed depressions or sinkholes. k clinker - bedrock that has been baked and fused as a result of a burning coal seam. L Tertiary landslide l landslide - earth and rock which became loosened from a hillside and slides, flows, or falls down the slope. M large open pit mine/quarry m mesa - a bedrock capped plateau or tableland. o glacial outwash - alluvium and drift deposited by meltwater streams beyond active glacier ice. p playa lake - broad, shallow sheets of water which quickly gather and evaporite, leaving mud flats or broad, shallow deposits. q periglacial deposits - patterened ground associated with nearby glaciated areas. R bedrock r residuum - a residual deposit remaining in place after the decomposition of rocks. s slopewash - soil and rock material that has been moved down a slope by gravity assisted by running water. T structural terrace - a terrace cut in bedrock that is mantled with a thin veneer of alluvium. T/t structural terrace and/or terrace deposits (could not be determined from aerial photos) t terrace deposits - relict alluvial deposits on relatively flat, horizontal, or gently inclined surfaces which are bounded by a steeper ascending slope on one side and by a steeper descending slope on the opposite side. u grus - an accumulation of angular, coarse- grained fragments resulting from the granular disintegration of crystalline rocks. v volcanic neck - cylindrical to spire-shaped form that is a remnant of solidified magma that filled the vent of an extinct volcano. w lacustrine deposits - deposits associated with lakes. x truncated, upturned bedrock The second phase of the classification combines the single elements into a multi-element classification for a specific mapping unit. In many cases, a specific mapping unit may be composed of many single elements, such as slopewash (s), colluvium (c), and bedrock (R), that in certain areas can not be shown separately at scales of 1:100,000 or 1:500,000. In such cases, the single elements were combined into a more complex unit (scR), with the single elements ranked from most dominant to least dominant. The mapping unit scR would then represent a complex deposit composed of slopewash, colluvium, and bedrock outcrops, with more slopewash present than either colluvium or bedrock outcrop. Approximately 650 complex units were mapped for the 1:100,000-scale map and 577 units were mapped for the 1:500,000-scale map, with a simple description of each unit presented in Appendix A. These complex units for the 1:500,000-scale map are stored in the attribute SG- UNIT. In order to achieve the objectives of the Ground-Water Vulnerability to Pesticide Contamination Project (Hamerlinck and Arneson, 1998), it was necessary to devise a classification scheme that was a simplification of the complex 650-unit scheme described above. A 25-element classification scheme that delineated simplified mapping units of most significance to contaminant migration was devised. The 25-element classification was composed of simple combinations of the single elements described above, and also included each of the 650 complex units as subsets. For example, the classification bi represents a bench that includes eolian, slopewash, outwash, and bench/mesa deposits. These attributes are stored in the layer item RECLASS. The complete association between the 25-element classification and the 650-unit classification is presented in Appendix B. The 25- element classification is presented below: Ai Old alluvial plain with scattered deposits of eolian, residuum, and slopewash ai Alluvium with scattered deposits of terrace, slopewash, eolian, residuum, grus and glacial aR Shallow Alluvium mixed with scattered bedrock outcrops bi Bench including eolian, slopewash, outwash, and bench and/or mesa bdi Dissected bench with scattered deposits of residuum, slopewash, landslide, and eolian tdi Dissected terrace deposits mixing with alluvium, residuum, eolian, and slopewash ti Terrace deposits mixed with scattered deposits of alluvium, residuum, eolian, slopewash, and outwash tre Shallow terrace deposits mixed with scattered deposits of eolian and residuum fi Alluvial fan and gradational fan deposits mixed with scattered deposits of slopewash, residuum, and eolian fdi Dissected alluvial fan and gradational fan deposits mixed with scattered deposits of slopewash and residuum mi Mesa including scattered deposits of residuum and eolian ei Eolian mixed with scattered deposits of residuum, alluvium, and slopewash oai Glacial outwash and alluvium mixed with scattered deposits of glacial, terrace, hot spring, bedrock outcrops, residuum, slopewash and grus gi Glacial deposits mixed with scattered deposits of slopewash, residuum, grus, alluvium, colluvium, landslide, and/or bedrock outcrops li Landslide mixed with scattered deposits of slopewash, residuum, Tertiary landslides, and bedrock outcrops; landslides too small and numerous to show separately pea Playa deposits mixed with scattered deposits of alluvium, eolian, and r; playa deposits too small to show separately sci Slopewash and colluvium mixed with scattered deposits of slopewash, residuum, grus, glacial, periglacial, alluvium, eolian, and/or bedrock outcrops ri Residuum mixed with alluvium, eolian, slopewash, grus, and/or bedrock outcrops ui Grus mixed with alluvium, eolian, slopewash, grus, and/or bedrock outcrops Ri Bedrock and glaciated bedrock including hot spring deposits and volcanic necks; mixed with scattered shallow deposits of eolian, grus, slopewash, colluvium, residuum, glacial, and alluvium. Mi Mined areas mixed with scattered deposits of residuum, slopewash, and/or bedrock outcrops Ki Karst areas mixed with scattered deposits of residuum, slopewash, alluvium and/or bedrock outcrops ki Clinker mixed with scattered deposits of residuum, slopewash, alluvium and/or bedrock outcrops xi Truncated bedrock mixed with scattered shallow deposits of eolian, terrace, residuum, alluvium, old alluvial plain, bench, and slopewash Ti Structural terrace including and/or mixed with deposits of alluvium, eolian, residuum, slopewash, and terrace. For a more detailed attribute listing, please see the citation below.
    Entity_and_Attribute_Detail_Citation:
    Case, J.C., Arneson, C.S., and Hallberg, L.L., 1998, Preliminary 1:500,000-scale digital surficial geology map of Wyoming: Wyoming State Geological Survey, Geologic Hazards Section Digital Map 98-1 (HDSM 98-1), scale 1:500,000.

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?

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

    Chris Arneson
    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?
The layer was developed by a partnership of the Wyoming State Geological Survey and the Wyoming Water Resources Center. It was originally created specifically for use in the Wyoming Ground-Water Vulnerability Mapping Project being conducted at the Wyoming Water Resources Center, a statewide study of aquifer vulnerability to contamination from pesticides. In that context, it was to be used to assist in the generation of a new State soils map, to analyze the effects of the vadose zone on contaminant migration, to define specific Quaternary- age aquifers, and to refine the analysis of regional hydrogeologic settings. The Surficial Geology Map of Wyoming can be used, in conjunction with a bedrock geologic map, as a guide in siting new facilities or industries in Wyoming. It can also be used to identify and locate geologic hazards, such as landslides and windblown deposits, or to assist in the search for shallow ground water supplies and for construction aggregate. The map has already been used to assist the Wyoming Gap Analysis Project (Merrill and others, 1997) in southwestern Wyoming, and in the generation of Quaternary Geologic Maps of Wyoming.

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

    NHAP photos (source 1 of 3)
    Survey, US Geological , unknown, National High Altitude Photography (NHAP).

    Type_of_Source_Media: film
    Source_Scale_Denominator: 58200
    Source_Contribution: photo interpretation of surficial geology

    BLM photos (source 2 of 3)
    US Bureau of Land Management, unknown, CPIR, RWIR, WWIR, RKSP series photography.

    Type_of_Source_Media: film
    Source_Scale_Denominator: 31680
    Source_Contribution: photo interpretation of surficial geology

    NRCS photos (source 3 of 3)
    US Natural Resources Conservation Service, unknown, AAM and BBT series photography.

    Type_of_Source_Media: film
    Source_Scale_Denominator: 20000
    Source_Contribution: photo interpretation of surficial geology

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

    Date: unknown (process 1 of 3)
    All citations mentioned are included in this report: Case, J.C., Arneson, C.S., and Hallberg, L.L., 1998, Preliminary 1:500,000-scale digital surficial geology map of Wyoming: Wyoming State Geological Survey, Geologic Hazards Section Digital Map 98-1 (HDSM 98-1), scale 1:500,000. Surficial geology was interpreted primarily using the NHAP photography. Color infrared BLM photos were used to provide detail in select areas of the stae. In northeastern Laramie County and southeastern Goshen County, black and white NRCS photos were used where NHAP photos were not available. In localized areas, additional photography from multiple sources and dates was used to fill small gaps in the NHAP coverage. The photography was analyzed by using a Fairchild Aviation Corporation Magnifying Mirror Stereoscope and an Abrams Instrument Corporation Pocket Stereoscope. Existing maps of surficial geology were examined, modified, and transferred to a 1:500,000-scale base map. In Yellowstone National Park and northern Teton County, existing surficial geologic maps of the area were modified to provide a classification consistent with the rest of the project (Pierce, 1973, 1974a, 1974b, 1974c; Richmond, 1973a, 1973b, 1973c, 1973d, 1974, 1977; Richmond and Pierce, 1971, 1972; Richmond and Waldrop, 1972, 1975; Waldrop, 1975a, 1975b; Waldrop and Pierce, 1975) In southwest Wyoming, existing surficial materials maps for the Kemmerer and Evanston 30' x 60' Quadrangles (Gibbons, 1986) were also modified, after examination of aerial photography, to provide a classification consistent with the rest of the project. In the Powder River Basin, existing surficial geologic maps for the Recluse 30' x 60' Quadrangle (Reheis and Williams, 1984), the Reno Junction 30' x 60' Quadrangle (Reheis and Coates, 1987), and the Gillette 30' x 60' Quadrangle (Reheis, 1987) were slightly modified to provide a classification consistent with the rest of the project. The Geologic Hazards Section at the Wyoming State Geological Survey has developed a series of techniques for mapping surficial features and deposits from aerial photography. Over the last sixteen years, Section personnel have mapped landslides, windblown deposits, active faults, and man-made features for the entire State of Wyoming. Much of the previous work has been accomplished by conducting a field examination of the area of interest, and then by applying the field examination to the interpretation of aerial photographs. Most of the interpretative techniques utilized in this project were derived from limited field examination in addition to standard aerial photo interpretation methodologies as defined in Von Bandat (1962), Reeves, Anson, and Landen (1975), Avery (1977), and Lillesand and Kiefer (1979). Surficial features and deposits were mapped at scales of 1:100,000 and 1:500,000. The smallest feature/deposit shown on the 1:100,000-scale map has a diameter or width of approximately 200 meters. At a scale of 1:500,000, the smallest feature/deposit shown has a diameter or width of approximately 500 meters. Material types are not delineated on the Surficial Geology Map of Wyoming. In parts of western Wyoming, the surficial geology was directly mapped at a scale of 1:500,000 by utilizing aerial photography, existing landslide maps, and existing geologic maps. The reasons for this approach in western Wyoming are that many of the surficial features were previously mapped landslides or glacial deposits, and that the terrain was distinct enough to allow for mapping at a scale of 1:500,000. In Teton County and northern Lincoln County, the geologic map of Grand Teton National Park (Love, Reed, and Christiansen, 1992), the geologic map of the Wyoming portion of the Driggs 1 x 2 (Love 1982), and the Geologic Map of Wyoming (Love and Christiansen, 1985) served as the basis for the surficial geology mapped from aerial photography. In the central parts of Lincoln County, the geologic maps of the Preston 1 x 2 Quadrangle (Oriel and Platt, 1980), the Geologic Map of Wyoming (Love and Christiansen, 1985), the Cokeville 30- Minute Quadrangle (Rubey, Oriel, and Tracey, 1980), and the Afton and part of the Big Piney 30-Minute Quadrangles (Rubey, 1973) served as the basis for the surficial geology mapped from aerial photography. In the Wind River Basin and surrounding mountains, the Structural Geology of the Wind River Basin, Wyoming (Keefer, 1970), the Geologic Map of Wyoming (Love and Christiansen, 1985), the Mineral Resources of the Teton Wilderness and Adjacent Areas (Antweiler and others, 1989), the Ground-Water Resources of the Wind River Indian Reservation, Wyoming (McGreevy, Hodson, and Rucker, 1969), and the Ground-Water Reconnaissance of the Green River Basin, Southwestern Wyoming (Welder, 1968) served as the basis for the surficial geology mapped from aerial photography. Landslides were derived from Case and others (1991) and Larsen and others (1991). Most of Wyoming was newly mapped at a scale of 1:100,000 by utilizing the previously mentioned photography. The reason for mapping most of the State at a scale of 1:100,000 instead of at a scale of 1:500,000 was that there was insufficient detail on existing 1:500,000-scale base layers to properly locate small features in the basins and in areas of low relief. All available geologic maps listed in Wyoming State Geological Survey Map Series 9A-9R (De Bruin, 1983, 1984, 1985; De Bruin and Greer, 1986; Glass, 1981; Greer and Ver Ploeg, 1989; King and Ver Ploeg, 1990) provided guidance for the mapping. Many of the 1:100,000-scale surficial geology maps contained too much detail to be transferred to the 1:500,000-scale base. In such areas, mapped units were combined before they were transferred to the 1:500,000- scale base, with every effort made to combine similar or related units. The same mapped units were not consistently combined, as the combinations were dependent only on the density of the mapped units in any area.

    Date: 1997 (process 2 of 3)
    The 1:500,000-scale inked green-line copy of the surficial geology linework drafted at the Wyoming State Geological Survey was scanned into ARC/INFO Version 6.21 at a 400 dpi (dots per inch) resolution by the Wyoming Water Resources Center GIS Lab. Because of the physical size of a 1:500,000-scale map of Wyoming, the map had to be scanned in three portions. Each of these portions was individually registered using latitude- longitude tic locations, and eventually rejoined. The RMS (Root Mean Squared) error in the registration procedure was limited to 0.006 inches as a standard. The scanned raster image was converted to a vector GIS format using ARC/INFO's GRIDLINE utility and then manually edited within ARCEDIT to remove any linework anomalies. In addition to removing slivers and other vectorization artifacts, a new state boundary was added that had been previously digitized at a scale of 1:100,000 as a part of the Wyoming Gap Analysis Project (Merrill and others, 1997). This boundary was added to ease the comparison with other 1:100,000-scale datasets previously created within the state. Quality control procedures, which consisted of plotting the new dataset at a scale of 1:500,000 and comparing it on a light- table to the original to detect linework errors and omissions, were then performed on the data. Once attributed, the dataset was once again checked for accuracy. Dissolve routines as well as extensive manual inspections were performed to identify unclosed polygons as well as mis-labeled polygons. After a thorough review by the WSGS, several small changes were made to the linework to add necessary additional detail. These changes were made using a digitizer and were limited to small areas in the western edge of the state. Once again the RMS error was limited to 0.006 inches. When the linework was finalized, 47,062 line segments were included as well as 16,608 individual polygons. Each polygon was attributed with the ten-digit character item SG-UNIT which contains the original surficial geology unit attribute. The domain of this field included the 577 original descriptions. Another field was later added to depict the simplified attributing scheme developed by the WSGS. This character field was called RECLASS and includes only the 25 simplified values. Currently the product can be referred to as Version 1.0 but additional errors may exist which will be fixed in future releases. It should be noted that if the product is viewed at a scale much larger than 1:500,000 the linework will appear jagged. This is an artifact remaining from the vectorization process that exists within the ARC/INFO software. No smoothing routines were performed on the linework in order to ensure that no error propogation exists.

    (process 3 of 3)
    Metadata imported.

    Data sources used in this process:

    • C:\DOCUME~1\decook\LOCALS~1\Temp\xml53.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?

    see Process Steps

  2. How accurate are the geographic locations?

    see Process Steps

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    All polygons are fully attributed.

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

    All polygons are closed and each polygon has one unique label.

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:
The data should not be used without first reading the full data documentation in WSGS HDSM 98-1. This data should not be used for analysis at a scale larger than 1:500,000. This dataset may not be redistributed or repackaged in any form without the express written consent of the Wyoming State Geological Survey and/or the Spatial Data and Visualization Center.

  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. 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: 26-May-1998

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 13:37:28 2004