The component feature classes show geologic units (polygons) and faults (lines.)
The nominal scale of the published hardcopy map is 1:500,000. In some areas data of greater scale were generalized and incorporated.
Illinois State Geological Survey, 2005, Bedrock Geology of Illinois: ISGS GIS Database GISDB_BEDGEO.IL_Bedrock_Geology_500K_2005, Illinois State Geological Survey, Champaign, Illinois.
Dennis Kolata, compiler, 2005, Bedrock Geology of Illinois: Illinois Map Series 14, 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.
Coordinates defining the features.
Sequential unique whole numbers that are automatically generated.
|3||New Albany Shale|
|7||Upper Pope Group|
|8||Lower Pope Group|
|9||St. Louis Limestone|
|10||Ste. Genevieve Limestone|
|11||Warsaw Fm and Salem Ls. in western Illinois|
|12||Meppen Ls, Fern Glen Fm, Burlington-Keokuk Ls.|
|13||Gen Park Fm, Hannibal Sh, Chouteau Ls, McCraney Ls, Prospect Hill St, and Starrs Cave Ls|
|14||Maquoketa Shale Group|
|18||Prairie du Chien Group|
|21||Shelburn-Patoka Fms undivided|
|27||Tertiary and Cretaceous Systems undivided|
|28||Permian ultramafic intrusions|
|30||Kimmswick Ls and Decorah Fm|
|31||Ft. Payne Fm, includes Springville Sh and Chouteau Ls in southern IL|
|32||Ullin and Salem Ls in southern IL|
|35||Bordon St, includes Chouteau Ls in east-central IL|
|999||not a geologic unit|
Positive real numbers that are automatically generated.
Positive real numbers that are automatically generated.
D. Kolata, P. Weibel, J. Nelson, C. McGarry, J. Devera, B. Denny, et al.
This data set was compiled to replace/update the existing feature dataset (IL_Bedrock_Geology_500K_1967), based on the 1967 Willman et al. Geologic Map of Illinois.
The 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.
, 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 were compiled from areas mapped at difference scales. Scale varies across the map. Some source data were generalized. The smallest scale of data used is 1:500,000, and that is the scale of the published map. Geologic unit boundaries are approximate.
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 digital data set, for example, geologic columns, cross-sections and other thematic insets. Quaternary materials are not shown.
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, firstname.lastname@example.org. 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 09:53:58 2009