Digitized Lithic Source Locations

All known lithic sources located on individual county maps have been digitized so this information can be coupled with the Excel lithic inventory for a GIS format. With the creation of a GIS for the Lithic Raw Material Assemblage, data can be use with a variety of base maps including Iowa Department of Transportation maps, 1:100,000 scale and 1:24,000 scale U.S.G.S. topographic maps (Figure 8). Orange areas indicate sample sites while the purple areas represent near or at surface bedrock as defined by the Geological Survey and Water Survey of the Iowa Department of Natural Resources. This has yielded a better picture of where our known lithic sources are. The Landform Regions of Iowa map will also be integrated into the GIS format for additional analytic potential. The current assemblage is the result of opportunistic sampling, leaving areas of the state possibly under represented or not represented at all. Additional samples are constantly being acquired and incorporated into the assemblage.

Figure 8. Lithic Source Map from Louisa County: 1:24,000 Scale

Figure 8. Lithic Source Map from Louisa County.


Each county folder contains three types of maps. The transportation map has “DOT” following the county abbreviation (i.e. AD-DOT = Adair County transportation map). All known lithic source sites are included on these maps for a county-wide view. The lithic source catalogue number followed by 100 or 24 identifies the 1:100,000 and 1:24,000 maps, respectively (i.e. AD-A-100 = Adair County sample A at 1:100,000 scale; AD-A-24 = Adair County sample A at 1:24,000). The key on the 1:100,000 and 1:24,000 scale maps contain lithic sample information including exposure identification number, lithic type, and exposure type. This data can be cross-referenced with the Excel data tables noted in the previous section. 

County Maps in Iowa: Geologic Sources