UNFINISHED BUSINESS – COMPLETING A MENTOR’S SURFICIAL GEOLOGIC MAPS

The National Park Service’s delineation of geologic resources along the Natchez Trace Parkway and National Scenic Trail (Natchez Trace) resulted in the need to finalize compilation and complete geologic maps that had been initiated by the author’s mentor and colleague Dr. E. E. Russell. The quadrangles include several in the Cretaceous outrcrop area in northeast Mississippi through which the Natchez Trace runs. The author had been asked to participate in the development of several of those, including the Tupelo, Mississippi 7.5 minute quadrangle. This process included field excursions by the author with Dr. Russell in surrounding areas within the Cretaceous outcrop area including the Marietta, Mississippi 7.5 minute quadrangle. After Dr. Russell’s death his family provided the author field maps, field books, field stratigraphic sections, and photographs from Dr. Russell’s mapping efforts (some of which the author had participated in developing).

Two new surficial geologic maps including shallow subsurface geology for the Tupelo and Marietta quadrangles have been compiled. In addition to the field data, USDA Natural Resources Conservation Service (NRCS) Soil Survey data and Mississippi Department of Environmental Quality, Office of Geology (MDEQ) geophysical logs were utilized to complete both quadrangles. Mississippi Department of Transportation borings and NRCS/US Geological Survey LIDAR data were also utilized in completing the Tupelo quadrangle. Neither of those two data sources were available for the Marietta quadrangle. Existing small scale geologic maps were also utilized but were of limited use due to their scale and age. The resulting geologic maps have been digitized and will be delivered to the National Park Service as a portion of the National Park Service Geologic Resources Inventory. The maps will then be published by the MDEQ.

Surficial units mapped on both quads were Cretaceous sediments with Quaternary alluvium and terrace deposits. The Cretaceous units on the Tupelo quadrangle are the Demopolis Formation chalk, and the Coffee Formation sands, including the Tupelo Tongue with the Mooreville Formation chalk in the shallow subsurface. The Cretaceous units on the Marietta quadrangle are the Coffee Formation sands and the Eutaw Formation sands, including the Tombigbee Sand.