Bedrock Geology of Illinois - Geologic Units

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Frequently-anticipated questions:


What does this data set describe?

Title: Bedrock Geology of Illinois - Geologic Units
Abstract:
This feature class shows the distribution and extent of the bedrock geologic units within the State of Illinois, as depicted on the Geologic Map of Illinois (1967) by Willman and others, published by the Illinois State Geologic Survey.
Supplemental_Information:
Detailed structural features are available in separate data sets.

Recent updates to the data:

In March 2004 edition 1.0 of the data set was transitioned to storage in an Oracle RDBMS using the ArcSDE geodatabase model. The result (this version) is designated Edition 20040331.

  1. How should this data set be cited?

    Illinois State Geological Survey, 1996, Bedrock Geology of Illinois - Geologic Units: ISGS GIS Database GISDB_BEDGEO.IL_Geologic_Units_500K_1967_Py, Illinois State Geological Survey, Champaign, Illinois.

    Online Links:

    Other_Citation_Details: The map scale is 1:500,000
    This is part of the following larger work.

    Willman, H. B. , Frye, John C. , Simon, Jake A. , Clegg, Kenneth E. , Swann, D. H. , Atherton, Elwood, Collinson, Charles, Lineback, Jerry, and Buschbach, T. C. , 1967, Geologic Map of Illinois: Geologic Maps Geologic map of Illinois 1967 edition, Williams and Heintz Map Corp., Capitol Heights, MD, USA.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -91.5826823
    East_Bounding_Coordinate: -87.38401652
    North_Bounding_Coordinate: 42.49563968
    South_Bounding_Coordinate: 36.95351896

  3. What does it look like?

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

    Calendar_Date: 1967
    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):

      • G-polygon (747)

    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 North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    BED-GEO - four digit numerical designator for name of geologic unit 1200 Tertiary - Undifferentiated 1360 Cretaceous - Undifferentiated 1550 Pennsylvanian - Mattoon 1880 Pennsylvanian - Bond 2120 Pennsylvanian - Modesto 2480 Pennsylvanian - Carbondale 3030 Pennsylvanian - Spoon 3540 Pennsylvanian - Abbott 3820 Pennsylvanian - Caseyville 4025 Mississippian - Upper Chesterian 4265 Mississippian - Lower Chesterian 5005 Mississippian - Upper Valmeyeran 5175 Mississippian - Middle Valmeyeran 5255 Mississippian - Lower Valmeyeran 5420 Mississippian - Kinderhookian 5810 Devonian - Upper 5880 Devonian - Middle 6170 Devonian - Lower 6700 Silurian - Undifferentiated 7390 Ordovician - Maquoketa 7550 Ordovician - Galena-Platteville 8160 Ordovician - Ancell 8420 Ordovician - Prairie du Chien 8550 Cambrian - Undifferentiated
    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?

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

    Contact_Instructions: Please refer to the Distribution Information section.


Why was the data set created?

These data can be used for any project which requires bedrock data at a scale of 1:500,000. This data should not be used at a scale larger than 1:500,000. Not suitable for site specific work.

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 1)
    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:
    geologic unit outlines and attributes, and fault lines.

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

    Date: Unknown (process 1 of 6)
    A mylar copy of this map was ordered from the publisher (William and Heintz). The mylar contained a state boundary, counties, township lines, geologic unit boundaries and labels. The map scale was 1:500,000.

    Date: unknown (process 2 of 6)
    A TIC coverage was created by plotting a copy of the townships coverage and comparing the township lines in this plot to those on the mylar. The township intersections which corresponded within linewidth accuracy were marked and used to create a TIC coverage.

    Date: unknown (process 3 of 6)
    Larger scale PMTs were created of the mylar coverage. These PMTs were used during the digitizing process. The statewide coverage was split into 3 separate areas (for there were 3 people digitizing) These were northwest, southwest and east. The arcs were digitized for each area and the areas combined to form a statewide bedrock geology map.

    Date: unknown (process 4 of 6)
    Once the linework had been checked (several times) the coverage was built as a polygon coverage. Labels were then created using the CREATELABELS command. A plot was then generated containing the labels for each polygon as well as the arcs. This plot was then compared to the published map and a table was created containing the polygon label and the code for the designated geologic unit. This table was entered into INFO and an item was added to both the poly coverage and the info table. A relate was established and the geologic values moved to the appropriate item in the polygon PAT.

    Date: unknown (process 5 of 6)
    The final coverage is a single precision coverage and had been cleaned with a fuzzy tol of 1 and dangle of 1. It was reviewed as described under data quality information.

    Date: 31-Mar-2004 (process 6 of 6)
    Source coverage (bedgeo) 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.

    Person who carried out this activity:

  3. What similar or related data should the user be aware of?

    , ISGS Terms of Use.

    Online Links:

    , University of Illinois Web Privacy Notice.

    Online Links:

    , University Copyright Policy (stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4).

    Online Links:

    , Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    The published paper geological map from the ISGS was the source for feature attributes. Attribute code assignments were checked by three individuals and are believed to 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 three individuals by visual comparison (manual overlay) of source maps 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 contains geologic units and fault lines as depicted on the source map. There are many additional features on the source map that are not depicted in this coverage, for example, geologic columns, cross-sections and other thematic insets. Quaternary materials are not shown.

  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. There are 116 dangling arcs representing the endpoints of fault lines as depicted on source maps.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
ISGS information must be obtained directly from the ISGS or from an authorized distributor. Be aware that ISGS information obtained from an unauthorized third party may have been altered subsequent to original distribution, or may no longer be current.

Any access to these data, Web sites, computer systems, electronic services, and electronic networks is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice.

Links to these are provided in the Cross References section.

Use_Constraints:
ISGS information is the property of and copyrighted by the Board of Trustees of the University of Illinois with all rights reserved.  University copyright policy is stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4. A link is provided in the Cross References section.

Individuals or entities may make fair use of copyrighted ISGS material, such as reproducing a single figure or table, or using a brief text quotation, without obtaining formal permission, but in all cases the Illinois State Geological Survey must be credited as the source of the material. To reproduce ISGS information beyond the fair use standard, permission must be obtained from the ISGS Information Office, 615 East Peabody Drive, Champaign, Illinois 61820, 217-333-4747, isgs@isgs.illinois.edu. License fees and a license agreement may be required, depending on the proposed usage.

Any use of these data is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. Links to these are provided in the Cross References section.

Map information is to be used at a scientifically and cartographically appropriate scale, that is, at a scale no greater than indicated on the map or as described in the documentation of the map or map data.  Map information is not appropriate for, and is not to be used as, a geodetic, legal, or engineering base. Map information has no legal basis in the definition of boundaries or property lines and is not intended as a substitute for surveyed locations such as can be determined by a registered Public Land Surveyor.

The data do not replace the need for detailed site-specific studies.

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

    Information Office, Illinois State Geological Survey (ISGS), a division of the Institute of Natural Resource Sustainability (INRS) of the University of Illinois
    615 East Peabody Drive
    Champaign, Illinois 61820
    USA

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

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

  3. What legal disclaimers am I supposed to read?

    Refer to the Legal Notices of Terms and Conditions of the University of Illinois Web Privacy Policy (there is a link in the Cross References section) for policy statements regarding the following:

    Disclaimer of Liability Disclaimer of Warranties and Accuracy of Data Disclaimer of Endorsement Disclaimer for External Links Disclaimer of Duty to Continue Provision of Data Security Choice of Law

    By obtaining these data you agree to the provisions of the University of Illinois Web Privacy Policy, regardless of the manner in which the information was obtained.

  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, ESRI formats can be imported into many different GIS software packages. It is expected that customers who obtain these 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: 24-Feb-2009
Metadata author:

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


Illinois Natural Resources Geospatial Data Clearinghouse

Generated by mp version 2.8.25 on Thu Apr 02 09:54:04 2009