Elevation of the Base of the Barlow Limestone [Illinois]
Description:
This datafile shows the general elevation of the base of the Barlow Limestone in Illinois.�� These 20- and/or 100-foot isolines were contoured using Geographix and Z-map Plus software.�� The contours were created using over 50,000 data points from the ISGS Oracle database.�� The data covers only those portions of the state where the formation is present and does not include any coverage outside of Illinois where the formation may be present.�� The data was contoured using fault lines for control and manual adjustments were made to the contours as a final refinement of the computer created contours.�� This data set is intended for use at a scale of 1:100,000 or greater. This data set was created as part of an effort to update some of the ISGS map products utilizing new data and software capabilities.�� This data set was developed in order to create an updated version of the map published by H.M. Bristol in 1968.�� These data are appropriate for use in local and regional thematic analysis.�� The data are not appropriate as a geodetic, legal or engineering base.
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