Origin of the data:
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.
Updates to the data:
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 (this one) is edition 1.1.
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.
These data are not to be used for commercial profit.
These data should not be used at scales greater than 1:500,000.
GIS processing: Environmental Systems Research Institute, Inc. (ESRI)
ISGS staff
Documentation: R. Krumm, D. Nelson and S. Beaverson
Quality Control: ISGS Staff, D. Nelson, A. Hansel
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 *path_name_suppressed*/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.
Attribute items are in typical ARC/INFO feature class format.
Those requiring additional explanation are:
Polygon attributes:
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
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.
Shift-click to download the data set and related documentation. (Data and metadata offered separately, please download both files.)
Illinois Natural Resources Geospatial Data Clearinghouse
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