This DEM is a mosaicked model of USGS 30x30 meter DEMs, showing 1:24,000-SCALE quadrangle map boundaries that extend in an irregular buffer outside the state boundary. The ISGS and USGS shared the cost to update a number of the DEMs from Level 1 (low quality) elevation data to Level 2 (best quality) to make this the highest resolution, statewide DEM coverage currently available. Due to budget constraints, an area in southeastern Illinois area has not been upgraded to Level 2 elevation data. The difference in quality is noticeable by the horizontal striping characteristic of Level 1 elevation data.
These data are appropriate for use in local and regional elevation analysis. The data are not appropriate as a geodetic, legal or engineering base. The data set can serve as an important base cartographic and analytical element for many types of maps. The data set was not and is not intended as a substitute for surveyed elevations, such as can be determined by a registered Public Land Surveyor.
Links to these are 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
Illinois Natural Resources Geospatial Data ClearinghouseGenerated by mp version 2.8.25 on Thu Apr 02 09:54:01 2009