U.S. Geological Survey
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Reston, VA 20192
Telephone: (703) 648-6907
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In the map area in east-central Illinois, extensive sands and gravels are buried within a thick sequence of glacial deposits. These sands and gravels constitute a highly productive regional aquifer, supplying water to numerous cities and communities. Through a collaborative effort between the Illinois State Geological Survey (ISGS) and the U.S. Geological Survey (USGS), the surficial, glacial deposits have been mapped using newly-developed 3-D mapping methods. The project's goals were to: 1) create a database of key stratigraphic information; 2) develop new methods for computer-aided mapping and presentation of data; 3) produce an integrated set of geologic maps and 3-D views for each glacial unit; and 4) use the geologic maps to help build a regional groundwater management tool.
The new mapping methods were described at the Digital Mapping Techniques workshop in 1998 (Soller, 1998, and http://pubs.usgs.gov/openfile/of98-487/soller4.html). These methods produced, in raster format, a set of maps of the complex subsurface geology that is internally consistent and that can form the geologic framework for a regional groundwater flow model. Three-dimensional views of each map were developed, to aid visualization. [Text, selected maps, and animated views of the images are available at http://ncgmp.usgs.gov/ecill/.] The maps and images were assembled into a formal USGS map product according to the following procedure.
In the study area, eight stratigraphic layers were mapped. For each layer, maps of unit elevation and unit thickness were created in Arc/Info Grid. Elevation data were imported into EarthVision, to create the 3-D images. The maps and screensaves of the images were converted to Postscript format. These files along with the photographs and text were imported into Adobe Illustrator where the composition of the formal USGS map product was completed. Plots generated on a HP3000 inkjet plotter at a resolution of 600 dpi served as proofs during the editing process, and as interim products. The high resolution of these interim plots made them highly effective tools for rapidly communicating the project's results to scientific audiences and to potential public- and private-sector cooperators in future projects.
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This site is http://pubs.usgs.gov/openfile/of99-386/soller3.html