Illinois State Geological Survey 1994 20040423 vector digital data ISGS GIS Database GISDB_QTGEO.IL_Drift_Thickness Champaign, Illinois Illinois State Geological Survey This is a feature dataset showing drift thickness in Illinois. Data are originally from ISGS Circular 490 by Piskin and Bergstrom (1975), Plate 1. Contours (lines) are coded with thickness, and polygons (areas between contours) are coded with range of thickness. Nominal scale is 1:500,000. Unconsolidated deposits, mainly glacial drift, overlie the bedrock surface in most of Illinois. Glacial drift ranges from less than a few feet to approximately 600 feet in thickness. The thickest drift occurs in major preglacial valleys cut into the bedrock and filled with glacial sediments. Regionally thick drift occurs in the N.E. portions of the state. The thinnest drift, less than 25 feet thick and intersected by numerous bedrock outcrops, occurs widely in southern and western portions of the State. Drift, as shown on this map, may include any of the following: unconsolidated deposits, glacial drift, Wisconsinan deposits, Illinoian deposits, till, glaciofluvial deposits, glaciolacustrine deposit, wind-blown deposits (loess). These data may be used to determine approximate depth to bedrock in regional areas of the state (eg. townships). The data are not of sufficient detail for use in determining drift thickness for specific locations. The data can be used for physical or environmental models of the state's unconsolidated geologic materials, eg. coupled with geophysical information, satellite imagery, air photos, hydrologic data, or other data in a Geographic Information System at a statewide scale of 1:500,000. 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. Recent updates to the data: In April 2004 edition 2.0 of the data set was transitioned to storage in an Oracle RDBMS using the ArcSDE geodatabase model. The result (this version) is designated Edition 20040423. Edition 1.0 of this data set was replaced edition 2.0 in June, 1998. The data were reviewed as described in the logical consistency report and process steps for May, 1998. Contour values, which were not included in edition 1.0, were included in version 2.0. 199410 Latest updates were made in 1994. Most of the data still reflect ISGS Circular 490 (1975). Complete Irregular -91.513518 -87.495214 42.508348 36.969972 none glacial drift unconsolidated till glaciofluvial glaciolacustrine loess driftless none Illinois none Wisconsinan Illinoian none Reproduction or redistribution of copyrighted digital data sets or products derived therefrom outside of licensee's organization or entity is expressly forbidden. The only exception is redistribution to consultants working for the licensee, and then only for purposes, related to work for the licensee. Such consultants may not further reproduce or redistribute these data sets. None of these data shall be electronically duplicated on magnetic or optical media for use by others, in whole or in part, without permission of DNR. 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. Please refer to the distribution information. ArcGIS 9.1 on Windows Attributes were verified against information on the source map by using polygon shading tied to attribute values. Checks were also performed by relating polygon and arc attribute tables and comparing polygon drift thickness range codes with arc drift thickness values. These checks were reiterated by three individuals. There are no known polygon or arc attribute values outside the appropriate domains. There were, however, some anomalous values discovered on the primary source map (Piskin and Bergstrom, 1975, Plate 1) that have been retained in this data set. See logical consistency report. Polygon and chain-node topology was present in the source coverage. It was 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. The data set meets these parameters. However, there exists at least one instance of anomalous contour labeling on the source map and in this data set. A pair of concentric contours exist in west-central Woodford County which should have a third contour around them labeled 100 feet. The missing contour does not appear on the source mylar for the map. The anomaly could not be reconciled, so it was left as it appeared on the original map. See the small "bulls-eye" contour in west-central Woodford County. See Piskin and Bergstrom (1975), ISGS Circular 490. Horizontal positional accuracy was verified by visual overlay of source and hard-copy plots. Arcs within line-width of source maps were deemed acceptable. For positional accuracy of source maps, see Piskin and Bergstrom (1975), ISGS Circular 490. Kemal Piskin & Robert E. Bergstrom 1975 map ISGS Circular 490 Champaign, Illinois Illinois State Geological Survey 500,000 paper 1975 publication date none polygon attributes Kemal Piskin & Robert E. Bergstrom 1975 map Champaign, Illinois Illinois State Geological Survey unpublished material 500,000 mylar 1975 publication date none drift thickness contours Environmental Systems Research Institute, Redlands CA 1984 maps and report 500000 paper 198411 publication date none data history The data (lines) were originally digitized and attributed by Environmental Systems Research Institute in 1984. 1984 The data was compared to the original mylar map at ISGS from the Circular 490 publication, and edits were made to make the digital map match the original mylar. Attribute coding remained the same. Editing was performed on a digitizing board using the original tics or registration points for the statewide coverage. 1984 The data set underwent quality assurance review in 1994. Many lines were smoothed and densified to provide a better match to the source mylars. In McDonough, Knox, and Fulton counties significant line edits were made where the digital lines did not match the mylar original (in most cases, due to collapsed arcs and/or carrying contours). 1994 Data set was reviewed in May, 1998. Review was limited to internal logical consistency of attribute items. Locations of features and accuracy of item values were not checked, except in cases where possible errors became apparent as a result of logical consistency checks. No checks were performed that involved plotting of hardcopy maps and manual overlay with source materials. Some changes were made, as follows: Arcs were coded with contour values. This was done with an AML program that assigned contour values to arcs based on the drift thickness values for the adjacent polygons. This processing was done in late 1996, but the updates were not posted to the general-use data set until June of 1998. 199806 199806 Source coverage (driftthk) 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. 20040423 Vector G-polygon 1354 0.000001 0.000001 Decimal degrees North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 IL_Drift_Thickness_Py FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. THICK RANGE Attribute items are in typical SDE feature class format. Those requiring explanation are: Polygon Attributes: THICK - thickness of drift 1 - Less than 25 feet 2 - 25 to 50 feet 3 - 50 to 100 feet 4 - 100 to 200 feet 5 - 200 to 300 feet 6 - 300 to 400 feet 7 - 400 to 500 feet 8 - Greater than 500 feet Thick. 9 - No Drift (Driftless Regions) RANGE - range of thicknesses in feet for that polygon Arc Attributes: CONTOUR - The contour value for the arc. Values of 999 indicate a line that is not a contour. none Illinois State Geological Survey, Quaternary Geology Section mailing and physical address

615 East Peabody Drive

Champaign Illinois 61820 USA 217-333-4747 217-785-0211 isgs@isgs.uiuc.edu 8:00 a.m. - 4:30 p.m., Monday - Friday, U.S. Central Time The Illinois Department of Natural Resources (DNR) provides these geographic data "as is." DNR makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. DNR further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these data have been processed successfully on computers of DNR, no warranty, expressed or implied, is made by DNR regarding the use of these data on any other system, nor does the fact of distribution constitute or imply any such warranty. 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. The data are intended for use with GIS software. The ISGS uses ESRI ArcGIS software, however, the ESRI shapefile format can be imported into many different GIS software packages. It is expected that customers who order this data have the technical expertise to use GIS software. The ISGS does not provide software support of any kind. 20060831 Please refer to the distribution information. FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time None. None. http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile