This layer originated with the Integrated Terrain Unit (ITU) digital data set prepared for the ISGS by Environmental Systems Research Institute, Inc. (ESRI) of Redlands, California in 1984.
The ITU manuscript synthesizes and organizes natural resource information for the state. Data included are natural divisions, bedrock geology, Quaternary geology, STACK units, glacial boundaries, soul associations, SCS land resource areas, ecoregions, and potential natural vegetation. The mapping resolution was generally 640 acres. Waterbodies were mapped to a minimum size of 320 acres. Data were integrated in the following order: Quaternary geology, stack units, glacial boundaries, bedrock geology, soil associations, natural divisions, potential natural vegetation, SCS land resource areas, and finally ecoregions.
Recent updates to the data:
In April 2004 edition 1.1 of the data set was transitioned to storage in an Oracle RDBMS using the ArcSDE geodatabase model. The result (this version) is designated Edition 20040423.
Edition 1.0 of these data were reviewed for internal logical consistency in May, 1998. As a result, tics were replaced, COVER-ID values were recalculated to be unique, and major revisions were made to polygon boundaries and attributes. See logical consistency report and process steps for May, 1998 for more details. The updated data set was edition 1.1.
Illinois State Geological Survey, 1998, Glacial Boundaries in Illinois: ISGS GIS Database GISDB_QTGEO.IL_Glacial_Bndys_Py, Illinois State Geological Survey, Champaign, Illinois.
This is a Vector data set. It contains the following vector data types (SDTS terminology):
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.
GLC-BND - Identifies the glacial episode (using the boundaries and diachronic terminology of Hansel and Johnson, 1996) 2 - Wisconsin 5 - Illinois 6 - Pre-Illinois 9 - Not glaciated
The data are appropriate as a statewide overview of the extent of the major glacial episodes in Illinois.
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.
J.A. Lineback, Illinois State Geological Survey, 1979, Quaternary Deposits of Illinois: Illinois State Geological Survey, Champaign, Illinois, USA.
Willman, H.B., 1967, Geologic Map of Illinois: Illinois State Geological Survey, Champaign, Illinois, USA.
Hansel, A. and H. Johnson, 1996, Wedron and Mason Groups: Lithostratigraphic Reclassification of Deposits of the Wisconsin Episode, Lake Michigan Lobe Area: Illinois State Geological Survey Bulletin 104, Illinois State Geological Survey, Champaign, Illinois, USA.
Some changes were made, as follows:
The existing set of tics was replaced by the set of tics from the coverage RE-STATE1. These were derived from 7.5 minute quadrangle corners (data set QUAD75) and give a good distribution of tics immediately outside the state boundary. COVER-ID values were recalculated to be unique. The existing state boundary line was replaced with the boundary from coverage state for general update purposes and to remove the portion of the state boundary that lies within the Lake Michigan area.
Most importantly, the spatial extent and attribute values of several polygons were changed to reflect the lithostratigraphic reclassification of deposits as described in ISGS Bulletin 104 (Hansel and Johnson, 1996). Specifically, polygons coded as Late, Middle or Early Woodfordian were amalgamated into a single polygon coded as Wisconsinan. Polygons coded as Altonian or Illinoian (undifferentiated) were amalgamated into a single polygon coded as Illinoian. Polygons coded as Kansan (undifferentiated) were recoded to Pre-Illinoian. Polygons coded as Not Glaciated were unchanged.
The features were imported into the ISGS SDE enterprise database following steps outlined in ISGS procedure GISDB_0009.
Person who carried out this activity:
, University of Illinois Web Privacy Notice.
, University Copyright Policy (stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4).
, Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign.
Data set information was reviewed by ISGS Staff. Information included is accurate in regard to Hansel and Johnson, ISGS Bull. 104. There are no known polygon attribute values outside the appropriate value domains.
In the ITU data preparation process, glacial boundary lines were adjusted to the boundaries of till members of a Quaternary geology overlay produced during the integration of stack-units and Quaternary geology units. In areas where glacial till was absent (i.e., bedrock, loess, and silt areas) the glacial boundaries were left unchanged. No quantitative assessment of horizontal accuracy is available. These data are intended to show a general statewide overview of the areal extent of glacial episodes. Use at scales greater than 1:500,000 is discouraged.
All known episodic boundaries that can be appropriately mapped at a scale of 1:500,000 are shown. There may exist site-specific studies containing more recent data that are not included here.
Polygon and chain-node topology was present in the source coverage. Typically, ISGS Arc/Info coverages are checked for complete chain-node topology (no dangling arcs, except where appropriate), polygon labels (one per polygon, except for universal polygon), boundary values appropriate for map projection and map units, and appropriate "fuzzy" tolerances.
Are there legal restrictions on access or use of the data?
- 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.
Links to these are provided in the Cross References section.
- 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, email@example.com. License fees and a license agreement may be required, depending on the proposed usage.
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.
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
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.
Illinois Natural Resources Geospatial Data ClearinghouseGenerated by mp version 2.8.25 on Thu Apr 02 09:54:04 2009