A knowledge of the engineering geologic characteristics of the Upper Cretaceous and lower Tertiary rocks is basic to assessing the effects of anticipated large-scale coal development in the Sweetwater-Kemmerer area of southwestern Wyoming. This development will include construction of railroads, highways, residences, and commercial and industrial installations, as well as surface and underground coal mines. Engineering geologic characteristics of the rocks and soils will affect all of these types of development. Engineering geologic characteristics, as used in this report, include the geotechnical properties of the various earth materials, and the behavior of these materials in natural and artificial slopes and in surface and underground coal mines. The geotechnical properties of the rocks both above and below the coal beds are important factors to consider in planning mining activities, because they control the behavior of the bedrock in response to either surface mining or underground mining. The properties of the rocks at the outcrop commonly may be so much altered from their natural state that geotechnical test results on these rocks can be false and misleading. It is commonly necessary to test drill cores in order to obtain adequate geotechnical information. The information necessary to properly evaluate the geotechnical properties of coal-bearing rocks in the Sweetwater-Kemmerer area is not currently available.
