It is usually buried by soil and vegetation, but in places such as mountain tops, stream banks, and road cuts it is often visible at the ground surface. A bedrock geologic map shows the distribution of rock types in an area. The geologist gathers information on rock type, mineralogy, and structure at as many bedrock exposures as possible, plots them on a topographic base, and draws contact lines between the various rock units. The resulting map shows the broad areas of different rock types, geologic contacts, and structural and mineralogical information. The map may include cross sections which present an interpretation of the geology below the ground surface.
Inset maps show tectonic and metamorphic features.
Bulletins and geologic quadrangle maps - maps and reports in the bulletin and geologic quadrangle map series represent the most advanced stage of geologic mapping in an area. The map is usually published in full color and is accompanied by a detailed report describing the rock units, mineralogy, structural geology, and other significant geologic aspects of the area. This material is available for inspection at the Survey's Augusta office. There is no index of available progress information. Return to the Geologic Fact Sheet home page.