Drone Geologic Mapping of an Active Sand and Gravel Quarry, Desoto County, Mississippi

Abstract

Aerial drone photography of an active pit within a sand and gravel quarry in DeSoto County, Mississippi, was conducted to better understand the Upland Complex, which is a high-level Pliocene terrace of the Mississippi River. The Upland Complex is of great interest economically, as it is the primary source of sand and gravel for Memphis, Tennessee and the surrounding region. The pit dimensions were approximately 820 ft (250 m) by 655 ft (200 m) and 79-ft (24 m) deep upon completion of the mining. Eight 3-D models of the pit were made at different times to illustrate the mining progression. Oblique and horizontal stereo aerial photography of the highwalls was conducted to produce 3-D models and high-resolution photomosaics of the highwalls for geologic mapping and interpretation. The mapped highwall geology included Pliocene Mississippi River bars consisting of sand, sand and gravel, and gravel ranging in thickness from 2 ft (0.6 m) to 32.8 ft (10 m), with variable cross-bed dip directions suggesting a meandering river environment of deposition. Pleistocene loess overlies the Pliocene sediment. The highwalls also revealed northerly-striking late Pliocene or Pleistocene tectonic folding, faulting, and probable earthquake liquefaction in northwestern Mississippi, where no Pliocene or Quaternary tectonic deformation had previously been reported. This study demonstrated Drone aerial photography as a quick, low cost, and safe means to study poorly accessible open-pit mining and to help understand the geology of the lower Mississippi River Valley.