Coarse-grained Materials Within 50 Feet of the Ground Surface in Illinois

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently-anticipated questions:


What does this data set describe?

Title:
Coarse-grained Materials Within 50 Feet of the Ground Surface in Illinois
Abstract:
This map shows the distribution of coarse-grained materials and permeable bedrock within 50 feet of ground surface in Illinois. This includes bedrock, sand and gravel, and alluvial units with characteristics that suggest a potential to store or conduct groundwater and yield potable water to wells and springs. It was derived from stack-unit map data. Aquifers or potential aquifers on this map are defined as sand and gravel units at least five feet thick, sandstone at least ten feet thick, and fractured limestone or dolomite at least fifteen feet thick with a lateral extent of at least one square mile. Minor aquifers typically yield from five to seventy gallons of potable water per minute. Potable water is defined as water containing less than 2,500 mg/L of total dissolved solids. For use in this data set, the following stratigraphic units are considered to be aquifers or potential aquifers meeting these criteria: (although Cahokia Alluvium is primarily fine-grained, it is included because it contains numerous sand and gravel deposits.)

Cahokia Alluvium Parkland Sand Equality Formation, Dolton Member Henry Formation Sand and gravel within Wedron Formation Sand and gravel within Winnebago Formation Pearl Formation (includes Hagarstown Member) Sand and gravel within Glasford Formation Mounds gravel and related units Cretaceous sediments, silts, sands, etc. Pennsylvanian rocks, mainly sandstones Mississippian rocks, mainly limestones, some sandstones Silurian and some Devonian rocks, mainly dolomite Ordovician and Cambrian rocks, mainly dolomite, some sandstone

The scale of these data is 1:250,000.

Supplemental_Information:
The coverage referred to in this documentation as STACK-ST was subsequently imported to the ISGS enterprise (SDE) database and is now known as GISDB_QTGEO.IL_Stack_Units_Py.

In April 2004 the source coverage was transitioned to storage in an Oracle RDBMS using the ArcSDE geodatabase model. The result (this version) is designated edition 20040401.

The source coverage (edition 2.0) was entirely reconstructed, making the previous version (coverage edition 1.0) obsolete. This edition retains the edition 2.0 data.

Revisions to the original version (edition 1.0) to produce edition 2.0: (1) coverage was entirely reconstructed from updated STACK-ST stack-unit map coverage (2) items SHADE and SYMBOL are no longer included (3) items MS (map symbol) and STACK-UNIT from coverage STACK-ST were added (4) some polygons that were erroneously included in version 1.0 have been removed. Specifically, These were 10-20 polygons containing stack-unit layers identified as loamy and sandy diamictons within the Glasford Formation. These units, identified in coverage STACK-ST with the code "q" or "Q", are not considered potential aquifers and are not included in this coverage.

  1. How should this data set be cited?

    M.H. Riggs, D. Nelson, C.C. Abert, 1997, Coarse-grained Materials Within 50 Feet of the Ground Surface in Illinois: ISGS GIS Database GISDB_HYDRO.IL_Shallow_Coarse_Materials_Py, Illinois State Geological Survey, Champaign, Illinois.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -91.4244
    East_Bounding_Coordinate: -87.3840
    North_Bounding_Coordinate: 42.4951
    South_Bounding_Coordinate: 36.9540

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 1996
    Currentness_Reference:
    These data were compiled from a variety of sources with publication dates generally ranging from 1970 to 1996. For a discussion of source materials see ISGS Circular 542 (Stack-unit mapping of geologic materials in Illinois to a Depth of 15 meters, Berg and Kempton, 1988) and the documentation for ISGS GIS coverage STACK-ST.

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • G-polygon (113)

    2. What coordinate system is used to represent geographic features?

      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.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    Attribute items are in typical SDE feature class format. Those requiring explanation are:

    CODE Identifies whether or not polygon is a potential aquifer as defined in this coverage. 0 - Not a potential aquifer 1 - Potential aquifer

    STACK-UNIT This item is a 15 digit numeric code that indicates 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 two digit identifier for unit name (see the table below). QUALx is a single digit 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 polygon area 2 - Drift unit 6m thick, locally less than 6m thick 3 - Drift unit < 6m thick, continuous throughout polygon area 4 - Drift unit < 6m thick, not continuous throughout polygon 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 concatenated (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 indicatenonlithified and semilithified units less than 6m (19.7 ft.) thick. Numbers unaccompanied by an asterisk indicatelithified units where the top occurs between depths of 6 to 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 to 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 polygon area but less than 6m thick in some areas. If the unit is the 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 polygon 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 15m. A number (with asterisk) enclosed by parentheses indicates the unit may not be continuous in the polygon area within 6m of surface, but is present between depths of 6-15m over a portion of the polygon area.


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Contact_Instructions: Please refer to the Distribution Information section.


Why was the data set created?

This feature class is intended to identify areas of Illinois where there is a potential for shallow aquifers to exist.

These data are appropriate for use in regional thematic analysis. The data are not appropriate as a geodetic, legal or engineering base. The datasets were not and are not intended as a substitute for surveyed locations, such as can be determined by a registered Public Land Surveyor. Although useful in a GIS, the data have no legal basis in the definition of boundaries or property lines.


How was the data set created?

  1. From what previous works were the data drawn?

    none (source 1 of 1)
    Illinois State Geological Survey, 1995, Stack-Unit Mapping of Geologic Materials in Illinois to a Depth of 15 Meters: ISGS GIS database GISDB_QTGEO.IL_Stack_Units_Py, Illinois State Geological Survey, Champaign, Illinois.

    Type_of_Source_Media: digital data
    Source_Scale_Denominator: 250000
    Source_Contribution: see process steps below

  2. How were the data generated, processed, and modified?

    Date: 15-Jan-1997 (process 1 of 6)
    The following Arc RESELECT selection set was used to create this coverage (codes conform to those listed under Entity and Attribute Overview): reselect stack-st poly ms cn a aselect stack-st poly ms cn A aselect stack-st poly ms cn d aselect stack-st poly ms cn D aselect stack-st poly ms cn g aselect stack-st poly ms cn G aselect stack-st poly ms cn h aselect stack-st poly ms cn H aselect stack-st poly ms cn o aselect stack-st poly ms cn O aselect stack-st poly ms cn v aselect stack-st poly ms cn V aselect stack-st poly ms cn R aselect stack-st poly ms cn r aselect stack-st poly ms cn z aselect stack-st poly ms cn M aselect stack-st poly ms cn m aselect stack-st poly ms cn K aselect stack-st poly ms cn k aselect stack-st poly ms cn W aselect stack-st poly ms cn 2 aselect stack-st poly ms cn 4 aselect stack-st poly ms cn 5 aselect stack-st poly ms cn 7 unsel stack-st poly ms cn water

    Date: 15-Jan-1997 (process 2 of 6)
    The state boundary from STACK-ST was copied, and the coverage was CLEANed with default tolerances.

    Date: 15-Jan-1997 (process 3 of 6)
    The item CODE was added, and every label was populated with CODE = 1. This marks every polygon extracted from STACK-ST as a potential aquifer.

    Date: 15-Jan-1997 (process 4 of 6)
    The CREATELABELS command was used to assign label points to the remaining polygons, being those that are considered "not potential aquifers." All user-defined item values for these polygons are either zeros (numeric items) or blanks (character items).

    Date: 22-Jan-1997 to 19970129 (process 5 of 6)
    The coverage was documented and QA review was initiated. See documentation for coverage STACK-ST for a description of its review process. The subsequent processing methodology and CODE item values were reviewed by ISGS staff. Comparison of this coverage (version 2.0) with the previous version (1.0) revealed some errors in version 1.0. Specifically, the previous version of the map included 10-20 polygons containing stack-unit layers identified as loamy and sandy diamictons within the Glasford Formation. These units, identified in coverage STACK-ST with the code "q" or "Q", are not considered potential aquifers and are not included in this coverage.

    Date: 01-Apr-2004 (process 6 of 6)
    Source coverage (aq50) 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.

    Person who carried out this activity:

  3. What similar or related data should the user be aware of?

    , ISGS Terms of Use.

    Online Links:

    , University of Illinois Web Privacy Notice.

    Online Links:

    , University Copyright Policy (stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4).

    Online Links:

    , Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    Attributes were extracted from ISGS data set STACK-ST, which was extensively reviewed and updated in 1995, including complete attribute verification checks by three individuals. Attribute codes are believed to fully representative of the source data. Source data were derived through contouring and interpretation. See ISGS Circular 542 (Stack-unit mapping of geologic materials in Illinois to a Depth of 15 meters, Berg and Kempton, 1988) for derivation methods.

  2. How accurate are the geographic locations?

    For the enitre state, locations of some features may be offset by 300 feet or more due to errors in the original source maps, the compilation process, digitizing, or a combination of these factors. For the areas immediately adjacent to the northern state boundary and the northern half of the Lake Michigan boundary, there is a potential positional error of up to 1250 feet, due to update of the state boundary. Horizontal positional accuracy of the source data set (STACK-ST) was verified by three individuals by visual comparison (manual overlay) of source mylar separates and hard-copy plots. Arcs within one line-width of source mylars were deemed acceptable. For accuracy of source data, consult Berg and Kempton, 1988, ISGS Circular 542.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    An earlier edition (1.0) of this dataset included 10-20 polygons containing stack-unit layers identified as loamy and sandy diamictons within the Glasford Formation. These units, identified in coverage STACK-ST with the code "q" or "Q", are not considered potential aquifers and are not included in this feature class.

    It is important to realize that characteristics which identify formations as potential aquifers do not imply that a particular unit is indeed an aquifer. For example, although Cahokia alluvium contains coarse-grained sand and gravel deposits which could store or conduct groundwater, it is predominantly a silty deposit associated with periodic flooding. Similarly, there are certainly existing shallow aquifers associated with other geologic formations not identified on this map. Because these data are generalized over a large areal extent, the user needs a good working knowledge of the geologic formations used here in order to derive valid and useful interpretations. Descriptions of the stratigraphic classifications used in this data set can be found in Willman and Frye, 1970, Pleistocene Stratigraphy of Illinois, ISGS Bulletin 94. Also, several of these stratigraphic units have since been reclassified. The user should consult Hansel and Johnson, 1996, Wedron and Mason Groups: Lithostratigraphic Reclassification of Deposits of the Wisconsin Episode, Lake Michigan Lobe Area, ISGS Bulletin 104.

  5. How consistent are the relationships among the observations, including topology?

    When in coverage format, this data set 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. There are no known polygon attribute values outside the appropriate value domains.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
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.

Any access to these data, Web sites, computer systems, electronic services, and electronic networks is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice.

Links to these are provided in the Cross References section.

Use_Constraints:
Suitable for regional applications only (1:250,000 scale or smaller). The Illinois State Geological Survey does not guarantee the validity or accuracy of these data. Data set is not to be redistributed.

It is important to realize that characteristics which identify formations as potential aquifers do not imply that a particular unit is indeed an aquifer. For example, although Cahokia alluvium contains coarse-grained sand and gravel deposits which could store or conduct groundwater, it is predominantly a silty deposit associated with periodic flooding. Similarly, there are certainly existing shallow aquifers associated with other geologic formations not identified on this map. Because these data are generalized over a large areal extent, the user needs a good working knowledge of the geologic formations used here in order to derive valid and useful interpretations. Descriptions of the stratigraphic classifications used in this data set can be found in Willman and Frye, 1970, Pleistocene Stratigraphy of Illinois, ISGS Bulletin 94. Also, several of these stratigraphic units have since been reclassified. The user should consult Hansel and Johnson, 1996, Wedron and Mason Groups: Lithostratigraphic Reclassification of Deposits of the Wisconsin Episode, Lake Michigan Lobe Area, ISGS Bulletin 104.

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, isgs@isgs.illinois.edu. License fees and a license agreement may be required, depending on the proposed usage.

Any use of these data is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. Links to these are provided in the Cross References section.

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.

  1. Who distributes the data set? (Distributor 1 of 1)

    Information Office, Illinois State Geological Survey (ISGS), a division of the Institute of Natural Resource Sustainability (INRS) of the University of Illinois
    615 East Peabody Drive
    Champaign, Illinois 61820
    USA

    217-333-4747 (voice)
    isgs@isgs.illinois.edu

    Hours_of_Service: 8:00 a.m. - 4:30 p.m., Monday-Friday, U.S. Central Time
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    Refer to the Legal Notices of Terms and Conditions of the University of Illinois Web Privacy Policy (there is a link in the Cross References section) for policy statements regarding the following:

    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

    By obtaining these data you agree to the provisions of the University of Illinois Web Privacy Policy, regardless of the manner in which the information was obtained.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    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.


Who wrote the metadata?

Dates:
Last modified: 24-Feb-2009
Metadata author:

Contact_Instructions: Please refer to the Distribution Information section.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


Illinois Natural Resources Geospatial Data Clearinghouse

Generated by mp version 2.8.25 on Wed Apr 08 08:29:07 2009