CHARACTERIZATION OF AEOLIAN SEDIMENTS AT SEVERAL LOCALITIES IN THE WHITE RIVER BADLANDS

As part of our first immersion into geological field investigations, we sampled and described four stratigraphic sections of aeolian sediments deposited upon tables in the lower prairie of badlands proximal to the White River, in South Dakota. Our objectives include gaining insight into provenance, determining the timing of deposition, and, potentially, correlating with intervals of aeolian activity and pedogenesis at other localities across the northern Great Plains. Across the White River Badlands, mesas are typically called tables, while sod tables are smaller remnants of dissected pediments that lie adjacent to the larger tables. Three localities were described on Skull Table, just south of SD 44 near Imlay on Conata Ranch. These exposures reveal 8-12 m of aeolian cliff-top deposits and loess sheets on the northern, windward edge of the table, thinning to 2-3 m at the leeward edge. At each locality, silt and sand beds were measured, described, and sampled for particle size analyses, and, for a subset, radiocarbon dating of bulk humate. Radiocarbon ages show deposition at the transition from Pleistocene to Holocene Epochs, or younger in the mid-Holocene. Particle size analyses were completed for the Skull Table samples which show abundances of sand, silt, and clay. The results show sand abundances of 49% to 76% with an average of 61%, silt ranges from 21% to 45% with an average of 31%, while clay ranges from 1% to 11% with an average value of 5%. Red Dog Table is the type locality for its namesake loess, which has been in use in mapping since 1968. Through these ongoing investigations of the White River Badlands, we seek to document significant intervals of aeolian and fluvial deposition, with effort to understand their paleoclimatic causalities.