These data are intended to be a regional overview of the extent of Quaternary geologic materials in the Alton quadrangle. The data are appropriate regional thematic analysis. The data are not appropriate as a geodetic or engineering base, nor do they replace the need for detailed site-specific studies.

1. From what previous works were the data drawn?

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

   Date: 1999 (process 1 of 1)

   Some contacts are based on NRCS soil reports for Madison County, Illinois, especially those for the Cahokia and Peyton Formations. There were modified based on topography and on many new field observations and well logs. Other contacts are based on ISGS geological records.

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

1. How well have the observations been checked?

   No attribute accuracy report.

2. How accurate are the geographic locations?

   No horizontal positional accuracy report.

3. How accurate are the heights or depths?

   No vertical positional accuracy report.

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

   No completeness report. Mapping techniques are described on the published map.

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

   A logical consistency review was performed in May, 2002. The following checks were made:

   Data set was DESCRIBED and coverage files listed to determine the feature types present. In this data set, the following feature types were found and checked: polygons, arcs, labels, and nodes. The presence of spatial indices was also checked.

   For PAT and AAT files, each ITEM was checked for the following:

   - DOMAIN of allowable values
   - adherence of values to the DOMAIN
   - definition of ITEMS
   - requirement of all UNIQUE values for an item
   - logic of ITEMS REDEFINED over other ITEMS
   - length of ITEM name as regards conversion to shape file
   

   BUILD statuses of data sets were checked, as were LABELERRORS and NODEERRORS (where appropriate), and PROJECTION definition.

   The presence of a DBLBND file was verified.

   The presence and location of TICS were checked.

   Polygon and chain-node topology present. There are no dangling arcs. There is one polygon label per polygon, except for universe polygon. Boundary values appropriate for map projection and map units. "Fuzzy" tolerance is zero and therefore meaningless. Unneeded .AAT and .PAT items were dropped and tics were replaced. Coverage was DISSOLVED to join polygons with like attributes. COVER-ID values were recalculated to be unique. There are no attribute values outside the appropriate domains.

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

Access_Constraints: none

Use_Constraints:

Reproduction or redistribution of copyrighted digital data sets or products derived therefrom outside of licensee 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 the appropriate custodial division within 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.

These data are not to be used for commercial profit.

These data should not be used at scales greater than 1:24,000.