Buried Bedrock Surface of Illinois

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Frequently-anticipated questions:

What does this data set describe?

Title: Buried Bedrock Surface of Illinois
Abstract:
The Buried Bedrock Surface of Illinois map represents the first revision of the bedrock topography map since the second edition was published by the Illinois State Geological Survey (Horberg, 1957). The map is useful for the regional and statewide studies such as groundwater resource planning and geologic mapping. The data included on this map were compiled by many downhole logging and surface studies. This information was combined to revise the bedrock topography map for the entire state. Since some of the most extensive and productive aquifers in the state are located in thick glacial sediments of major buried bedrock valleys, special attention was given to data for known bedrock valleys. The revised map was published by the ISGS (Herzog et al, 1994) and much of the following text appears on the published map.

The bedrock topography is shown as 50-foot (15-meter) contours of bedrock elevation above mean sea level (msl). Bedrock elevations range from less then 250 feet (76 meters) in southern Illinois to more than a 1000 feet (300 meters) in the northwestern part of the state. Several major bedrock valleys are found across the state.

The greatest control for the present bedrock surface configuration was probably the preglacial surface configuration. The interpretations of bedrock topography have been modified since the 1950's. Horberg contoured his map with the philosophy that the bedrock surface map represented the preglacial topography modified by glacial erosion, which formed U-shaped valleys. The current map, showing narrow valley channels and bedrock knobs in wide channels, indicates complex preglacial and glacial erosion primarily from running water. The major valleys were formed before the minor valleys that appear as tributaries. Streams that formed during successive glaciations probably eroded to bedrock and produced the small tributary valleys to the main channels. The bedrock surface was less likely to be eroded as sediments accumulated during each successive glaciation.

Supplemental_Information:
The dataset was transferred for storage into the ISGS Enterprise GIS (SDE) in March, 2004. At that time the edition number was changed from 1.0 to 20040331.
  1. How should this data set be cited?

    Herzog, B.L.. B.J. Stiff, C.A. Chenoweth, K.L, 1994, Buried Bedrock Surface of Illinois: ISGS GIS Database GISDB_BEDGEO.IL_Bedrock_Topography_1994_Ln, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details:
    Scale is 1:500,000. This is the digital version of ISGS Map Series, Illinois Map 5.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -91.58050943
    East_Bounding_Coordinate: -87.38825182
    North_Bounding_Coordinate: 42.49669441
    South_Bounding_Coordinate: 36.9521143

  3. What does it look like?

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

    Calendar_Date: 1994
    Currentness_Reference: 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):

      • String (2620)

    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 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is NAD27.
      The ellipsoid used is CLARKE1866.
      The semi-major axis of the ellipsoid used is 6378206.4 meters.
      The flattening of the ellipsoid used is 1/294.98.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    Attribute items are in typical SDE feature class format. Those requiring additional explanation are:

    CONTOUR The elevation above msl in Lambert feet. Values range from 200 to 1000 with a contour interval of 50 feet. A value of zero (0) is used to indicate the state boundary or areas where bedrock is at or near the surface.

    Entity_and_Attribute_Detail_Citation: none
    IL_Bedrock_Topography_1994_Ln

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    CONTOUR

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?

    Contact_Instructions: Please refer to distribution information.

Why was the data set created?

Applications are regional or statewide studies, preferably at a scale of 1:500,000.

The Buried Bedrock Surface of Illinois will be useful in fields such as groundwater resource planning, engineering geology and earthquake hazard mapping. Data shown on this map were compiled from geologic data from drill holes, samples, surface observations and geophysical data from downhole logging and surface studies.

The data are not appropriate as a geodetic, legal or engineering base. The data set was not and is not intended as a substitute for surveyed locations, such as can be determined by a registered Public Land Surveyor. Although useful in a GIS as a reference base layer for maps, the data set has no legal basis in the definition of boundaries or property lines.

How was the data set created?

  1. From what previous works were the data drawn?

    none (source 1 of 27)
    Herzog, B.L.. B.J. Stiff, C.A. Chenoweth, K.L, 1994, Buried Bedrock Surface of Illinois: ISGS Illinois Map series 5, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 500000
    Source_Contribution: contour attributes (elevation values)

    none (source 2 of 27)
    Herzog, B.L.. B.J. Stiff, C.A. Chenoweth, K.L, 1994, Original mylar separates for map of Buried Bedrock Surface of Illinois: Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: unpublished material
    Type_of_Source_Media: mylar
    Source_Scale_Denominator: 500000
    Source_Contribution: contour lines

    none (source 3 of 27)
    Anderson, R.C., 1980, Geology for Planning in Rock Island County, Illinois: ISGS Circular 510, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 35 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 4 of 27)
    Berg, R.C., J.P. Kempton, A. Stecyk, 1984, Geology for Planning in Boone and Winnebago Counties: ISGS Circular 531, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 69 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 5 of 27)
    Bristol, B.B. and P.R. Seaber, 1973, Ordovician Galena Group of Illinois-Structure and Oil Fields, Plate 1: Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 6 of 27)
    Curry, B.B. and P.R. Seaber, 1990, Hydrogeology of Shallow Groundwater Resources, Kane County, Illinois: Contract/Grant Report 1990-1, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 7 of 27)
    Greasse, A.M., R.A. Bauer, B.B. Curry, R.C. Va, 1988, Geological-Geotechnical Studies for Siting Superconducting Super Collider in Illinois: ISGS Environment notes 123, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 8 of 27)
    Heigold, P.C. and R.W. Ringler, 1979, A seismic Refraction Survey of the Lower Illinois Valley Bottomlands: ISGS Circular 507, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 18 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 9 of 27)
    Horberg, L., 1950, Bedrock Topography of Illinois: ISGS Bulletin 73, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 10 of 27)
    Horberg, L., 1957, Bedrock Surface of Illinois: Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 500000
    Source_Contribution: not available

    none (source 11 of 27)
    Hunt, C.S. and J.P. Kempton, 1971, Geology for Planning in DeWitt County, Illinois: ISGS Environmental Geology Notes 83, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 42 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 12 of 27)
    Jacobs, A.M. (compiler), 1971, Geology for Planning in St. Clair County, Illinois: ISGS Circular 465, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 35 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 13 of 27)
    Kempton, J.P., W.H. Johnson, P.C. Heigold and , 1991, Mahomet Bedrock Valley in east-central Illinois: Geological Society of America (GSA) Special Paper 285.

    Other_Citation_Details: p. 91
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 14 of 27)
    Kempton, J.P., W.H. Morse, and A.P. Visocky, 1982, Hydrogeologic Evaluation of Sand and Gravel Aquifers and Municipal Groundwater Supplies in east-central Illinois: Cooperative Groundwater/Resources Report 8, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 15 of 27)
    Kempton, J.P., R.W. Ringler, P.C. Heigold, K. , 1981, Groundwater Resources of Northern Vermillion County, Illinois: Environmental Groundwater/Resources Report 13, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 36 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 16 of 27)
    Kempton, J.P. A.P. Visocky, 1992, Regional Groundwater Resources in East McLean and Tazewell County: Mahomet Bedrock Valley: Cooperative Groundwater/Resources Report 13, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 42 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 17 of 27)
    Kolata, D.R., T.C. Buschbach and J.D. Treworg, 1978, The Sandwich Fault Zone of Northern Illinois: ISGS Circular 505, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: Figure 2
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 18 of 27)
    Larsen, J.I, 1973, Geology for Planning in Lake County, Illinois: ISGS Circular 481, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 43 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 19 of 27)
    Larson, D.R., B.L. Herzog, R.C. Vaiden, C.A. , 1994, Hydrogeology of the Green River Lowland and Associated Bedrock Valleys of Northwest Illinois: Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 43 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 20 of 27)
    Larson T.H. and V.L. Poole, 1989, Geophysical Exploration of Potential Groundwater Resources near Bloomington, Illinois: ISGS Contract/Grant Report 1989-2, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 51 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 21 of 27)
    Lineback, J.A., 1979, Quaternary Deposits of Illinois: ISGS map same as title, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 500000
    Source_Contribution: not available

    none (source 22 of 27)
    Palmer, R.A. (compiler), 1983, The Decade of North American Geology (DNAG) 1983 Geologic Time Scale: Geology, v 11 no. 9.

    Other_Citation_Details: p. 503-504
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 23 of 27)
    Piskin, K. and R.E. Bergstrom, 1975, Glacial Drift in Illinois: Thickness and Character: ISGS Circular 490, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 35 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 500000
    Source_Contribution: not available

    none (source 24 of 27)
    Richmond, M.R. and D.S. Fullerton, 1986, Introduction to Quaternary Glaciation in the United States of America: Quaternary Science Review v5.

    Other_Citation_Details: p. 130
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 25 of 27)
    Walker W.H., R.E. Bergstrom and W.C. Walton, 1965, Report on the Groundwater Reservoir of the Havana Region in West-Central Illinois: Cooperative Groundwater/Resources Report 3, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 61 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: not available
    Source_Contribution: not available

    none (source 26 of 27)
    H. B. Willman, John C. Frye, Jake A. Simon, Kenneth, 1967, Geologic Map of Illinois: ISGS map same as title, Williams and Heintz Map Corp., Capitol Heights, MD.

    Type_of_Source_Media: mylar map
    Source_Scale_Denominator: 500,000
    Source_Contribution: not available

    none (source 27 of 27)
    Willman, H.B., and J.C. Frye, 1980, The Glacial Boundary in Southern Illinois: ISGS Circular 511, Illinois State Geological Survey, Champaign, Illinois.

    Other_Citation_Details: 23 p.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 500000
    Source_Contribution: not available

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

    Date: 1994 (process 1 of 8)
    Note: This entire section is taken directly from the published Buried Bedrock Surface map (Herzog et al, 1994). Horberg's work was updated by incorporating more detailed, published maps and unpublished data. This map was prepared for publication by combining computer techniques with traditional methods.

    Date: 1994 (process 2 of 8)
    Well log data from the ISGS files were entered into an ISGS computer database created for this project. Data compilation concentrated on areas where Horberg mapped bedrock valleys. More well information was available for the northern 35 counties, where many densely populated communities depend on groundwater supplies, than for the rest of the state.

    Date: 1994 (process 3 of 8)
    Well locations with bedrock elevation data plotted by computer at a scale 1:250000. Bedrock topography was manually contoured for separate maps of the northern, central, and southern parts of the state, then the maps were manually combined. Anomalous bedrock elevation data were rechecked with the original source and compared with other data for the area, Horberg's maps, and previously published regional local bedrock topography maps. Glacial margins are from Lineback (1979). The style of Horberg (1957) was followed by not contouring bedrock elevation beyond the glacial margin, except where the bedrock surface is overlain by thick river alluvium and outwash. Sizeable areas are shown where the bedrock surface within and beyond the glacial margin is within approximately 20 feet (6 meters) or less of the ground surface. Beyond the glacial margin, the bedrock surface may be covered by river alluvium, outwash, loess, or residuum.

    Date: 1994 (process 4 of 8)
    After the map was assembled by hand, local and regional bedrock topography maps, published since Horberg (1957), were incorporated into this bedrock topography map. Unlike the state map, the regional and local maps used all data available for the areas under study at the time of publication. These maps were modified with new data and spliced into the hand-contoured map. Locations of these maps are shown in an inset map (figure 1) on the published (hardcopy) version of this map. Sources of the regional maps are listed in the references.

    Date: 1994 (process 5 of 8)
    The contours were first hand-drafted onto a 1:250000-scale base map. The base included reference points at latitude/longitude degree intersections. The manually drafted contours and reference points were scanned to convert the line to digital format. Because of size limitations of the equipment, the map was scanned in eight parts. The resulting digital images were converted to a vector format, spatially referenced, edited, labeled with elevation values, and combined to form one map.

    Date: 1994 (process 6 of 8)
    This data has gone though several review steps. The published version of the Buried Bedrock Surface Map went through an internal review process prior publication in 1993.

    (process 7 of 8)
    Source coverage (bedtopo) converted to double precision and reprojected to GCS_NAD83 using Workstation ArcInfo 7.2.1.

    The features were imported into the ISGS SDE enterprise database following steps outlined in ISGS procedure GISDB_0009.

    Metadata updated.

    Date: 04-Oct-2004 (process 8 of 8)
    A user reported that the contour value for OBJECTID = 938 was in error. It was 600 but should be 550. The value was corrected.

    Person who carried out this activity:

  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?

    The published geological map (ISGS Illinois Map 5, 1994) was the source for feature attributes. Attribute code assignments were reviewed by both the ISGS and the USGS and are believed to be fully representative of the source document.

  2. How accurate are the geographic locations?

    Horizontal positional accuracy of this data with respect to the source map was verified by ISGS and USGS personnel by visual comparison (manual overlay) of source mylars and hard-copy plots. Arcs within one line-width of source mylars were deemed acceptable.

  3. How accurate are the heights or depths?

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

    This data set depicts the buried bedrock surface of Illinois. Areas where the bedrock surface is exposed at the surface are not shown (e.g. the northwest Illinois driftless area, and much of southern Illinois).

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

    When in coverage format, this data set was checked for complete chain-node topology (no dangling arcs, except where appropriate), boundary values appropriate for map projection and map units, and appropriate "fuzzy" tolerances. There are no known arc attribute values outside the appropriate value domains.

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:
This coverage should be used at 1:500,000 scale or smaller (ie: 1:1,000,000).

Reproduction or redistribution of copyrighted digital data sets or products derived therefrom outside of licensee's organization or entity is expressly forbidden. The only exception is redistribution to consultants working for the licensee, and then only for purposes, related to work for the licensee. Such consultants may not further reproduce or redistribute these data sets. None of these data shall be electronically duplicated on magnetic or optical media for use by others, in whole or in part, without permission of DNR.

Any hardcopies utilizing DNR data sets shall clearly indicate their source. If the licensee has modified the data in any way they are obligated to describe the types of modifications they have performed on the hardcopy map. Licensee specifically agrees not to misrepresent DNR data sets, nor to imply that changes they made were approved by DNR.

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

    Illinois State Geological Survey, Bedrock Geology Section
    615 East Peabody Drive
    Champaign, Illinois 61820
    USA

    217-333-4747 (voice)
    isgs@isgs.uiuc.edu

    Hours_of_Service: 8:00 a.m. - 4:30 p.m., Monday - Friday, U.S. Central Time
    Contact_Instructions:
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    The Illinois Department of Natural Resources (DNR) provides these geographic data "as is." DNR makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. DNR 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 of DNR, no warranty, expressed or implied, is made by DNR regarding the use of these data on any other system, nor does the fact of distribution constitute or imply any such warranty.

    In no event shall the DNR 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 DNR.

  4. How can I download or order the data?

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

    The data are intended for use with GIS software. The ISGS uses ESRI ArcGIS software, however, the ESRI shapefile format can be imported into many different GIS software packages.

    It is expected that customers who order this data have the technical expertise to use GIS software. The ISGS does not provide software support of any kind.

Who wrote the metadata?

Dates:
Last modified: 31-Jul-1998
Metadata author:

Contact_Instructions: Please refer to the distribution information.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Illinois Natural Resources Geospatial Data Clearinghouse

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