Stack-unit maps show the distribution of earth materials vertically from the surface to a specified depth and horizontally over a specified area They also show the succession of geologic units in their order of occurrence within the specified depth. This information is now available for the entire state of Illinois with the publication of the statewide stack-unit map of geologic materials to a depth of 15 meters (49.3 ft.).
The statewide stack-unit map, originally made up of four separate regional maps, provides basic geologic information for interpretive mapping for regional, resource-based land-use planning and decision making. This feature class is the result of appending the four separate digital files into one statewide dataset. Note also that this feature class incorporates stack-unit data from the ISGS Paducah Stack-Unit map (Berg and Greenpool, 1994). The portion that falls within the 1 x 2 degree Paducah quadrangle had been entirely updated with data from the Paducah stack-unit map coverage.
Depth is a significant factor for most resource and land-use interpretations derived from stack-unit data. For example, in the evaluation of sites for municipal landfills, geologic material to a depth of 15 meters should be documented. For near-surface or surficial waste-disposal practices, for evaluation of materials for shallow construction purposes, or assessment of recharge, detailed information in the upper 6 meters is usually the most important. For mineral resource evaluation, the thickness of overburden and thickness and character of the resource must be considered. Likewise, for shallow groundwater resource evaluation, the thickness, continuity, and depth of an aquifer, as well as the properties of overlying materials, must be recognized.
Statewide stack-unit data have been used to produce interpretive maps for projects such as municipal, surface and near surface waste disposal (susceptability to contamination), and shallow aquifer identification. They can be used to appraise (1) regional geologic conditions, (2) general geologic conditions that might affect excavation and construction of roads, pipelines or sewers, and (3) possible locations of mineral resources, particularly sand and gravel, clay, peat, limestone and dolomite.
This feature class is appropriate for use at scales of 1:250,000 and smaller.
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.
In April 2004 edition 2.1 of the data set was transitioned to storage in an Oracle RDBMS using the ArcSDE geodatabase model. The result (this version) is designated Edition 20040422.
Edition 2.0 of these data were reviewed for internal logical consistency in June, 1998. As a result, tics were replaced, COVER-ID values were recalculated to be unique, and an empty annotation feature class was dropped. The updated data set was edition 2.1.
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.
Also, the state boundary has been updated with detailed data from the ISGS Illimap database. A notable result of this update was that parts of the northern and northeastern boundaries of the state were shifted south and west up to 1500 feet. This is due to (1) the original northern boundary on STACK1 being digitized as a straight line, while the updated boundary is the more accurate latitudinal arc segment; and (2) the coastline of the greater Chicago area being better represented on the updated boundary. Specifically, the boundaries were moved: approx. 300 ft. south at the NW and NE corners of the state, and approx. 1500 ft. south at the center point of the northern boundary, and; from 0 to approx. 1500 ft. west in the Chicago shoreline vicinity. Note that no rubbersheeting took place, so any inconsistencies introduced by this operation are strictly localized to the boundary areas.
Subsequent updates:
2-17-95 Clark Co. area was updated with more recent data.
3-27-95 Made approx. 30 label updates to coverage.
Revisions made to data:
Prior to the processing of 1994, no revision numbers had been assigned to this coverage. Thus, the original coverages will be arbitrarily assigned revision number 1 and this updated version will be revision number 2.
The features were imported into the ISGS SDE enterprise database following steps outlined in ISGS procedure GISDB_0009.
Metadata updated.
STACK-UNIT The STACK-UNIT item is a 15 digit numeric code that describes up to five geologic units present, their order of occurrence, and general thickness and depth. It is directly related to item MS in that MS is an alphanumeric designator that represents the same information as STACK-UNIT. STACK-UNIT consists of ten concatenated (redefined) items called (and in this order) UNIT1, QUAL1, UNIT2, QUAL2, UNIT3, QUAL3, UNIT4, QUAL4, UNIT5, QUAL5. UNITx (where x is 1, 2, 3, 4, or 5) is a 2 digit field unit name (see the table below). QUALx is a qualifier for each UNITx, giving thickness, depth and continuity information for the corresponding UNITx. For example, QUAL1 contains a code that gives descriptive information for UNIT1. UNIT1 is the uppermost unit, UNIT5 is the lowermost unit.
TABLE OF ITEM RELATIONSHIPS UNITx MSx Corresponding Geologic Unit (MAP-SYMBOL)
(nonlithified and semilithified materials) 1 A a* Cahokia Alluvium 2 Y y* Peyton Colluvium 3 B b* Richland Loess 4 C c* Peoria and Roxana Loess 5 D d* Parkland Sand 6 E e* Grayslake Peat 7 F f* Equality Formation, Carmi Member 8 G g* Equality Formation, Dolton Member 9 H h* Henry Formation 10 I i* Wedron Formation, silty and clayey diamictons 11 J j* Wedron Formation, loamy and sandy diamictons 12 K Sand and gravel within Wedron Formation: 12 k* within 6 m (19.7 ft.) of surface 26 z* between 6-15 m (19.7-49.3 ft.) of surface 13 L l* Winnebago Formation, mainly sandy diamictons 14 M Sand and gravel within Winnebago Formation: 14 m* within 6 m (19.7 ft.) of surface 26 z* between 6-15 m (19.7-49.3 ft.) of surface 15 N n* Teneriffe Silt 16 O o* Pearl Formation (includes Hagarstown Member) 17 P p* Glasford Formation, silty and clayey diamictons 18 Q q* Glasford Formation, loamy and sandy diamictons 19 R Sand and gravel within Glasford Formation 19 r* within 6 m (19.7 ft.) of surface 26 z* between 6-15 m (19.7-49.3 ft.) of surface 22 U u* Wolf Creek Formation (mainly diamictons) 23 V v* Mounds gravel and related units 24 W w* Cretaceous sediments, silts, sands, etc. 25 X Surface mines/man-made land
(lithified materials) 41 1 1* Pennsylvanian rocks, mainly shales 42 2 2* Pennsylvanian rocks, mainly sandstones 43 3 3* Mississippian rocks, mainly shales 44 4 4* Mississippian rocks, mainly limestones, some sandstones 45 5 5* Silurian and some Devonian rocks, mainly dolomite 46 6 6* Ordovician rocks, mainly shale (Maquoketa Group) 47 7 7* Ordovician and Cambrian rocks, mainly dolomite, some sandstone
other 98 water body of water
QUALx 1 Drift unit > 6m thick, continuous throughout map area 2 Drift unit > 6m thick, locally less than 6m thick 3 Drift unit < 6m thick, continuous throughout map area 4 Drift unit < 6m thick, not continuous throughout map area
6 Bedrock unit present between 6 and 15 meters below surface 7 Bedrock unit not present continuously between 6 and 15 meters below surface; locally present at or just below 15 meters 8 Bedrock unit present within 6 meters of surface 9 Bedrock unit not present continuously above 6 meters below surface; but then is present between 6-15 meters
MS Item MS is the map symbol for each polygon. It is an alphanumeric character set that describes up to five geologic units present, their order occurrence, and general thickness and depth. Item MS is directly related to item STACK-UNIT in that STACK-UNIT is a strictly numeric designator that represents the same information as item MS. MS consists of five concatenate (redefined) items called MS1, MS2, MS3, MS4, MS5. Each redefined MSx (where x is 1, 2, 3, 4, 5) item represents a single geologic unit, MS1 being the uppermost and MS5 being the lowermost. Uppercase letters indicate nonlithified a semilithified units greater than 6m (19.7 ft.) thick. Lowercase letters accompanied by asterisk indicate nonlithified and semilithified units less than 6m (19.7 ft.) thick. Numbers unaccompanied by an asterisk indicate lithified units where the top occurs between depths of 6-15m (19.7-49.3 ft.) below ground surface. Numbers accompanied by an asterisk indicate lithified units where the top occurs between depths of 0-6m (0-19.7 ft.) below ground surface.
Some units are of varying thickness; this is represented by parentheses. An uppercase letter enclosed by parentheses indicates the unit is continuous throughout the map area but less than 6m thick in some areas. If the unit is lowermost, it may not be present above the 15m depth, but generally lies at just below 15m.
A lowercase letter (with asterisk) enclosed by parentheses indicates the unit is not continuous throughout the map area. If the unit is lowermost it may not be present above the 15m depth, but generally lies at or just below 15m.
A number (without asterisk) enclosed by parentheses indicates the unit may not be present above the 15m depth, but generally lies at or just below that depth.
A number (with asterisk) enclosed by parentheses indicates the unit may not be continuous in the map area within 6m of surface, but is present between depths of 6-15m over a portion of the map area.
Refer to the table above for the relationship between MS, STACK-UNIT, and name of the corresponding geologic unit.
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.
Illinois Natural Resources Geospatial Data Clearinghouse
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