POTENTIAL LINKAGES BETWEEN GLOBAL CLIMATE VARIATION AND AEOLIAN ACTIVITY IN THE WHITE RIVER BADLANDS DUNE FIELDS, SOUTH DAKOTA, NORTHERN GREAT PLAINS, USA

Worldwide, aeolian activity correlates with periods of landscape destabilization, often caused by increased aridity during prolonged periods of drought referred to as megadroughts. Preserved aeolian landscapes provide insight into the intensity and regional extent of drought events. The White River Badlands (WRB) dune field, a relatively small dune field located in southwestern South Dakota, 60 km upwind of the western Nebraska Sand Hills, is one of the northernmost dune fields in the western Great Plains. Understanding the timing of aeolian activity in the WRB is critical to distinguishing local versus regional and global climate forcing events, as well as determining provenance of midcontental sand and loess on the central Great Plains.

Previous work constructed a chronology of WRB aeolian activity using 37 optically stimulated luminescence (OSL) ages of samples collected from the crests of dunes and cliff exposures on mesas, known locally as tables, throughout the WRB. These OSL data suggest aeolian erosion and stabilization occurred near the ends of Late Pleistocene and Holocene cold periods: Cluster 1, the Late Glacial; Cluster 2, the Younger Dryas; Cluster 3, the 8.2 ka event; and Cluster 4, the Little Ice Age. In addition to the temporal groupings, OSL ages show distinct spatial patterns. The oldest ages (Cluster 1) occur only in cliff exposure samples and have not been detected in the aeolian landforms of the tables. All other ages show a spatial distribution with older ages (Cluster 2) in the northwestern portions of the tables and younger toward the southeast.

Together, the spatial and temporal relationships suggest the following conceptual model for development of the present-day aeolian landscape. 1- Deposition of the tabletop sands during the Late Glacial. 2- Reworking of the Late Glacial sands into a Younger Dryas dune field. 3- Continued reworking during the 8.2 ka Event, resulting in southeast shift of deposition . 4- Dune reactivation and migration during the Little Ice Age. Evidence of aeolian activity during the Dust Bowl droughts consists of aerial photographs of scattered blowouts. The conceptual model will be used in future work to develop sampling and survey programs to verify this proposed model of evolution.