529 OUT OF 804 AND COUNTING: RECENT 7.5-MINUTE QUADRANGLE SCALE GEOLOGIC MAPPING BY THE TENNESSEE GEOLOGICAL SURVEY

Recognizing the societal value of detailed geologic maps, the state of Tennessee initiated a statewide geologic mapping program in 1962. The Tennessee Geological Survey’s mandate is to economically investigate, compile, and disseminate the results of our geologic mapping efforts. Since the start of the program, the Survey, with the assistance of the U.S. Geological Survey, has completed 529 out of 804 7½-minute quadrangles across the state. In order to achieve our annual statewide mapping objectives, the Survey relies on the financial assistance of the USGS State Geologic Mapping Program element of the National Cooperative Geologic Mapping Program.

The members of the Tennessee Mapping Advisory Committee provide a range of perspectives for best utilizing the limited resources of the Survey to meet current and future geologic map information needs. In order to best serve the citizens of Tennessee, a long range mapping plan divides the state into three distinct project areas: (1) West Tennessee Coastal Plain, (2) Big South Fork National River and Recreation Area, and (3) East Tennessee Transportation Corridor. The three project areas were designated in 2009 based on the state-wide distribution of existing 7½-minute geologic maps, as well as the important societal benefits obtained by completing maps in these areas.

We recognize that once a map is completed it is unlikely that the area will be revisited in the foreseeable future and therefore use this opportunity to make as detailed a geologic map as possible. The approach to geologic mapping, however, is not the same in each of the project areas. In West Tennessee, field mapping is augmented by hand-augering to depths as great as 40 feet to better assess the distribution of Paleogene and Quaternary deposits. In the Big South Fork National River and Recreation Area, field mapping of Mississippian and Pennsylvanian strata on the Plateau is aided by the relative abundance of oil and gas well logs. In East Tennessee, the increased structural complexity of the Paleozoic strata in the fold-thrust belt and paucity of subsurface data requires an ample number of field traverses to constrain the geologic map interpretation. Our purpose is to provide a summary of recently completed geologic maps and to present the criteria used to select future priority maps within each of the project areas.