Identification_Information: Citation: Citation_Information: Originator: Herzog, B.L.. B.J. Stiff, C.A. Chenoweth, K.L. Warner, J.B. Sievering, C. Avery Publication_Date: 1994 Title: Buried Bedrock Surface of Illinois Edition: 20040331 Geospatial_Data_Presentation_Form: map Series_Information: Series_Name: ISGS GIS Database Issue_Identification: GISDB_BEDGEO.IL_Bedrock_Topography_1994_Ln Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: Scale is 1:500,000. This is the digital version of ISGS Map Series, Illinois Map 5. Description: Abstract: The Buried Bedrock Surface of Illinois map represents the first revision of the bedrock topography map since the second edition was published by the Illinois State Geological Survey (Horberg, 1957). The map is useful for the regional and statewide studies such as groundwater resource planning and geologic mapping. The data included on this map were compiled by many downhole logging and surface studies. This information was combined to revise the bedrock topography map for the entire state. Since some of the most extensive and productive aquifers in the state are located in thick glacial sediments of major buried bedrock valleys, special attention was given to data for known bedrock valleys. The revised map was published by the ISGS (Herzog et al, 1994) and much of the following text appears on the published map. The bedrock topography is shown as 50-foot (15-meter) contours of bedrock elevation above mean sea level (msl). Bedrock elevations range from less then 250 feet (76 meters) in southern Illinois to more than a 1000 feet (300 meters) in the northwestern part of the state. Several major bedrock valleys are found across the state. The greatest control for the present bedrock surface configuration was probably the preglacial surface configuration. The interpretations of bedrock topography have been modified since the 1950's. Horberg contoured his map with the philosophy that the bedrock surface map represented the preglacial topography modified by glacial erosion, which formed U-shaped valleys. The current map, showing narrow valley channels and bedrock knobs in wide channels, indicates complex preglacial and glacial erosion primarily from running water. The major valleys were formed before the minor valleys that appear as tributaries. Streams that formed during successive glaciations probably eroded to bedrock and produced the small tributary valleys to the main channels. The bedrock surface was less likely to be eroded as sediments accumulated during each successive glaciation. Purpose: Applications are regional or statewide studies, preferably at a scale of 1:500,000. The Buried Bedrock Surface of Illinois will be useful in fields such as groundwater resource planning, engineering geology and earthquake hazard mapping. Data shown on this map were compiled from geologic data from drill holes, samples, surface observations and geophysical data from downhole logging and surface studies. 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. Supplemental_Information: The dataset was transferred for storage into the ISGS Enterprise GIS (SDE) in March, 2004. At that time the edition number was changed from 1.0 to 20040331. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1994 Currentness_Reference: publication date Status: Progress: Complete Maintenance_and_Update_Frequency: Irregular Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -91.58050943 East_Bounding_Coordinate: -87.38825182 North_Bounding_Coordinate: 42.49669441 South_Bounding_Coordinate: 36.9521143 Keywords: Theme: Theme_Keyword_Thesaurus: none Theme_Keyword: geology Theme_Keyword: bedrock Theme_Keyword: topography Place: Place_Keyword_Thesaurus: none Place_Keyword: Illinois Access_Constraints: none Use_Constraints: This coverage should be used at 1:500,000 scale or smaller (ie: 1:1,000,000). 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. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Instructions: Please refer to distribution information. Data_Set_Credit: Native_Data_Set_Environment: ArcGIS 9.1 on Windows Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The published geological map (ISGS Illinois Map 5, 1994) was the source for feature attributes. Attribute code assignments were reviewed by both the ISGS and the USGS and are believed to be fully representative of the source document. Logical_Consistency_Report: When in coverage format, this data set was checked for complete chain-node topology (no dangling arcs, except where appropriate), boundary values appropriate for map projection and map units, and appropriate "fuzzy" tolerances. There are no known arc attribute values outside the appropriate value domains. Completeness_Report: This data set depicts the buried bedrock surface of Illinois. Areas where the bedrock surface is exposed at the surface are not shown (e.g. the northwest Illinois driftless area, and much of southern Illinois). Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal positional accuracy of this data with respect to the source map was verified by ISGS and USGS personnel by visual comparison (manual overlay) of source mylars and hard-copy plots. Arcs within one line-width of source mylars were deemed acceptable. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Herzog, B.L.. B.J. Stiff, C.A. Chenoweth, K.L. Warner, J.B. Sievering, C. Avery Publication_Date: 1994 Title: Buried Bedrock Surface of Illinois Geospatial_Data_Presentation_Form: map Series_Information: Series_Name: ISGS Illinois Map series Issue_Identification: 5 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Source_Scale_Denominator: 500000 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1994 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: contour attributes (elevation values) Source_Information: Source_Citation: Citation_Information: Originator: Herzog, B.L.. B.J. Stiff, C.A. Chenoweth, K.L. Warner, J.B. Sievering, C. Avery Publication_Date: 1994 Title: Original mylar separates for map of Buried Bedrock Surface of Illinois Geospatial_Data_Presentation_Form: map Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: unpublished material Source_Scale_Denominator: 500000 Type_of_Source_Media: mylar Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1994 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: contour lines Source_Information: Source_Citation: Citation_Information: Originator: Anderson, R.C. Publication_Date: 1980 Title: Geology for Planning in Rock Island County, Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Circular Issue_Identification: 510 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 35 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1980 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Berg, R.C., J.P. Kempton, A. Stecyk Publication_Date: 1984 Title: Geology for Planning in Boone and Winnebago Counties Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Circular Issue_Identification: 531 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 69 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1984 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Bristol, B.B. and P.R. Seaber Publication_Date: 1973 Title: Ordovician Galena Group of Illinois-Structure and Oil Fields, Plate 1 Geospatial_Data_Presentation_Form: report Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1973 Source_Currentness_Reference: not available Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Curry, B.B. and P.R. Seaber Publication_Date: 1990 Title: Hydrogeology of Shallow Groundwater Resources, Kane County, Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: Contract/Grant Report Issue_Identification: 1990-1 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1990 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Greasse, A.M., R.A. Bauer, B.B. Curry, R.C. Vaiden, W.G. Dixon, Jr., J.P. Kempton Publication_Date: 1988 Title: Geological-Geotechnical Studies for Siting Superconducting Super Collider in Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Environment notes Issue_Identification: 123 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1988 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Heigold, P.C. and R.W. Ringler Publication_Date: 1979 Title: A seismic Refraction Survey of the Lower Illinois Valley Bottomlands Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Circular Issue_Identification: 507 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 18 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1979 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Horberg, L. Publication_Date: 1950 Title: Bedrock Topography of Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Bulletin Issue_Identification: 73 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1950 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Horberg, L. Publication_Date: 1957 Title: Bedrock Surface of Illinois Geospatial_Data_Presentation_Form: map Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Source_Scale_Denominator: 500000 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1957 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Hunt, C.S. and J.P. Kempton Publication_Date: 1971 Title: Geology for Planning in DeWitt County, Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Environmental Geology Notes Issue_Identification: 83 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 42 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1971 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Jacobs, A.M. (compiler) Publication_Date: 1971 Title: Geology for Planning in St. Clair County, Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Circular Issue_Identification: 465 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 35 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1971 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Kempton, J.P., W.H. Johnson, P.C. Heigold and K. Cartwright Publication_Date: 1991 Title: Mahomet Bedrock Valley in east-central Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: Geological Society of America (GSA) Special Paper Issue_Identification: 285 Other_Citation_Details: p. 91 Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1991 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Kempton, J.P., W.H. Morse, and A.P. Visocky Publication_Date: 1982 Title: Hydrogeologic Evaluation of Sand and Gravel Aquifers and Municipal Groundwater Supplies in east-central Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: Cooperative Groundwater/Resources Report Issue_Identification: 8 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1982 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Kempton, J.P., R.W. Ringler, P.C. Heigold, K. Cartwright, V.L. Poole Publication_Date: 1981 Title: Groundwater Resources of Northern Vermillion County, Illinois Series_Information: Series_Name: Environmental Groundwater/Resources Report Issue_Identification: 13 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 36 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1981 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Kempton, J.P. A.P. Visocky Publication_Date: 1992 Title: Regional Groundwater Resources in East McLean and Tazewell County: Mahomet Bedrock Valley Series_Information: Series_Name: Cooperative Groundwater/Resources Report Issue_Identification: 13 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 42 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1992 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Kolata, D.R., T.C. Buschbach and J.D. Treworgy Publication_Date: 1978 Title: The Sandwich Fault Zone of Northern Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Circular Issue_Identification: 505 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: Figure 2 Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1978 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Larsen, J.I Publication_Date: 1973 Title: Geology for Planning in Lake County, Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Circular Issue_Identification: 481 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 43 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1973 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Larson, D.R., B.L. Herzog, R.C. Vaiden, C.A. Chenoweth and R.C. Anderson Publication_Date: 1994 Title: Hydrogeology of the Green River Lowland and Associated Bedrock Valleys of Northwest Illinois Geospatial_Data_Presentation_Form: report Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 43 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1994 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Larson T.H. and V.L. Poole Publication_Date: 1989 Title: Geophysical Exploration of Potential Groundwater Resources near Bloomington, Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: ISGS Contract/Grant Report Issue_Identification: 1989-2 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 51 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1989 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Lineback, J.A. Publication_Date: 1979 Title: Quaternary Deposits of Illinois Geospatial_Data_Presentation_Form: map Series_Information: Series_Name: ISGS map Issue_Identification: same as title Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Source_Scale_Denominator: 500000 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1989 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Palmer, R.A. (compiler) Publication_Date: 1983 Title: The Decade of North American Geology (DNAG) 1983 Geologic Time Scale Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: Geology, v 11 Issue_Identification: no. 9 Other_Citation_Details: p. 503-504 Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1989 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Piskin, K. and R.E. Bergstrom Publication_Date: 1975 Title: Glacial Drift in Illinois: Thickness and Character Geospatial_Data_Presentation_Form: map and report Series_Information: Series_Name: ISGS Circular Issue_Identification: 490 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 35 p. Source_Scale_Denominator: 500000 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1975 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Richmond, M.R. and D.S. Fullerton Publication_Date: 1986 Title: Introduction to Quaternary Glaciation in the United States of America Series_Information: Series_Name: Quaternary Science Review Issue_Identification: v5 Other_Citation_Details: p. 130 Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1975 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Walker W.H., R.E. Bergstrom and W.C. Walton Publication_Date: 1965 Title: Report on the Groundwater Reservoir of the Havana Region in West-Central Illinois Geospatial_Data_Presentation_Form: report Series_Information: Series_Name: Cooperative Groundwater/Resources Report Issue_Identification: 3 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 61 p. Source_Scale_Denominator: not available Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1975 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: H. B. Willman, John C. Frye, Jake A. Simon, Kenneth E. Clegg, D. H. Swann, Elwood Atherton, Charles Collinson, Jerry Lineback, and T. C. Buschbach. Publication_Date: 1967 Title: Geologic Map of Illinois Geospatial_Data_Presentation_Form: map Series_Information: Series_Name: ISGS map Issue_Identification: same as title Publication_Information: Publication_Place: Capitol Heights, MD Publisher: Williams and Heintz Map Corp. Source_Scale_Denominator: 500,000 Type_of_Source_Media: mylar map Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1967 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Source_Information: Source_Citation: Citation_Information: Originator: Willman, H.B., and J.C. Frye Publication_Date: 1980 Title: The Glacial Boundary in Southern Illinois Geospatial_Data_Presentation_Form: map and report Series_Information: Series_Name: ISGS Circular Issue_Identification: 511 Publication_Information: Publication_Place: Champaign, Illinois Publisher: Illinois State Geological Survey Other_Citation_Details: 23 p. Source_Scale_Denominator: 500000 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1975 Source_Currentness_Reference: publication date Source_Citation_Abbreviation: none Source_Contribution: not available Process_Step: Process_Description: Note: This entire section is taken directly from the published Buried Bedrock Surface map (Herzog et al, 1994). Horberg's work was updated by incorporating more detailed, published maps and unpublished data. This map was prepared for publication by combining computer techniques with traditional methods. Process_Date: 1994 Process_Step: Process_Description: Well log data from the ISGS files were entered into an ISGS computer database created for this project. Data compilation concentrated on areas where Horberg mapped bedrock valleys. More well information was available for the northern 35 counties, where many densely populated communities depend on groundwater supplies, than for the rest of the state. Process_Date: 1994 Process_Step: Process_Description: Well locations with bedrock elevation data plotted by computer at a scale 1:250000. Bedrock topography was manually contoured for separate maps of the northern, central, and southern parts of the state, then the maps were manually combined. Anomalous bedrock elevation data were rechecked with the original source and compared with other data for the area, Horberg's maps, and previously published regional local bedrock topography maps. Glacial margins are from Lineback (1979). The style of Horberg (1957) was followed by not contouring bedrock elevation beyond the glacial margin, except where the bedrock surface is overlain by thick river alluvium and outwash. Sizeable areas are shown where the bedrock surface within and beyond the glacial margin is within approximately 20 feet (6 meters) or less of the ground surface. Beyond the glacial margin, the bedrock surface may be covered by river alluvium, outwash, loess, or residuum. Process_Date: 1994 Process_Step: Process_Description: After the map was assembled by hand, local and regional bedrock topography maps, published since Horberg (1957), were incorporated into this bedrock topography map. Unlike the state map, the regional and local maps used all data available for the areas under study at the time of publication. These maps were modified with new data and spliced into the hand-contoured map. Locations of these maps are shown in an inset map (figure 1) on the published (hardcopy) version of this map. Sources of the regional maps are listed in the references. Process_Date: 1994 Process_Step: Process_Description: The contours were first hand-drafted onto a 1:250000-scale base map. The base included reference points at latitude/longitude degree intersections. The manually drafted contours and reference points were scanned to convert the line to digital format. Because of size limitations of the equipment, the map was scanned in eight parts. The resulting digital images were converted to a vector format, spatially referenced, edited, labeled with elevation values, and combined to form one map. Process_Date: 1994 Process_Step: Process_Description: This data has gone though several review steps. The published version of the Buried Bedrock Surface Map went through an internal review process prior publication in 1993. Process_Date: 1994 Process_Step: Process_Description: Source coverage (bedtopo) 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. Time_of_Day: 11214300 Process_Step: Process_Contact: Contact_Information: Contact_Person_Primary: Process_Description: A user reported that the contour value for OBJECTID = 938 was in error. It was 600 but should be 550. The value was corrected. Process_Date: 20041004 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: String Point_and_Vector_Object_Count: 2620 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geodetic_Model: Horizontal_Datum_Name: NAD27 Ellipsoid_Name: CLARKE1866 Semi-major_Axis: 6378206.4 meters Denominator_of_Flattening_Ratio: 294.98 Geographic: Geographic_Coordinate_Units: Decimal degrees Latitude_Resolution: 0.000001 Longitude_Resolution: 0.000001 Vertical_Coordinate_System_Definition: Altitude_System_Definition: Entity_and_Attribute_Information: Overview_Description: Entity_and_Attribute_Overview: Attribute items are in typical SDE feature class format. Those requiring additional explanation are: CONTOUR The elevation above msl in Lambert feet. Values range from 200 to 1000 with a contour interval of 50 feet. A value of zero (0) is used to indicate the state boundary or areas where bedrock is at or near the surface. Entity_and_Attribute_Detail_Citation: none Detailed_Description: Entity_Type: Entity_Type_Label: IL_Bedrock_Topography_1994_Ln Attribute: Attribute_Label: FID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: Shape Attribute_Definition: Feature geometry. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Coordinates defining the features. Attribute: Attribute_Label: CONTOUR Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Illinois State Geological Survey, Bedrock Geology Section Contact_Address: Address_Type: mailing and physical address Address: 615 East Peabody Drive City: Champaign State_or_Province: Illinois Postal_Code: 61820 Country: USA Contact_Voice_Telephone: 217-333-4747 Contact_TDD/TTY_Telephone: 217-785-0211 Contact_Electronic_Mail_Address: isgs@isgs.uiuc.edu Hours_of_Service: 8:00 a.m. - 4:30 p.m., Monday - Friday, U.S. Central Time Contact_Instructions: Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Distribution_Liability: 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. Technical_Prerequisites: 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. Metadata_Reference_Information: Metadata_Date: 19980731 Metadata_Contact: Contact_Information: Contact_Instructions: Please refer to the distribution information. Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Use_Constraints: None Metadata_Time_Convention: local time Metadata_Extensions: Online_Linkage: http://www.esri.com/metadata/esriprof80.html Profile_Name: ESRI Metadata Profile Metadata_Access_Constraints: None