T179 Quaternary Climate from the Great Plains to the Great Basin: Geomorphic and Sediment Records across “Great” Landscapes

Tuesday, 11 October 2022
1:30 PM - 5:30 PM
505

SKULL TABLE: AN OUTCROP LOCALITY FEATURING AEOLIAN, COLLUVIAL, AND ALLUVIAL LANDSCAPE INTERACTIONS, WHITE RIVER BADLANDS

Paper number: T179-13
Program: Technical Sessions
Time: 4:30 PM – 4:45 PM

Authors

Abstract

The buttes, sod tables, and relict dunes of the White River Badlands, South Dakota, hold a record of climate-affected landscape development throughout the Quaternary. Here, we report a new locality south of Highway 44 in the lower prairie of the White River Valley, Pennington County. At this location, referred to as “Skull Table,” a loess sheet ~ 10m thick on the northern windward edge, but thinning to 1.5m elsewhere, caps the butte, and is actively being incorporated into a pediment attached to the retreating slope. This loess may be correlative to the Holocene Bignell Loess of Nebraska. Some pediments have been incised and isolated from further deposition, forming ‘sod tables,’ which can provide valuable insight into the timing of incision. Paleosols in the deposits get cross-cut by the incision, so they constrain the maximum age for that dissection. The interfingering of eroding loess within the pediment and sod tables presents an opportunity to integrate our research of wind-blown deposits into our examination of sod tables, landscape incision, and slope retreat. Previous work has suggested that sod tables in the region were incised during the late Holocene, perhaps in association with aridity during the Medieval Climate Anomaly or the Little Ice Age. In order to help elucidate the ages of these deposits, we are processing radiocarbon ages of paleosols in the loess which caps Skull Table and paleosols within the sod tables. We are also completing grainsize analyses and bulk geochemistry to determine the provenance of the loess. Our goal is to better understand Late Pleistocene through Holocene paleoclimate through the record of landscape perturbation, including the timing of discernable events (such as pediment incision). We also wonder if the current megadrought is triggering incision of pediments across the American West, as we postulate that such has occurred in the past, and if dune fields will also reactivate as the vegetation complex withers.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-383480

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