Climactic Transition and Loess Transport in the White River Badlands, South Dakota

Climactic Transition and Loess Transport in the White River Badlands, South Dakota

Alvin Sherman Library

The Great Plains is one of the most important agricultural regions in the world. However, the semiarid climate makes the region vulnerable to drought and climate change. Safeguarding this critical resource will depend on forecasting the timing and magnitude of climatic transitions and drought events. This study investigates dust deposition during the climate transition from the last glacial period into the modern interglacial period (Late Pleistocene to Holocene) in the White River Badlands (WRB), South Dakota. Preliminary radiocarbon evidence indicates significant dust deposition began around 25,000 years ago (25 ka), coinciding with the coldest time during the last glacial period (Last Glacial Maximum). However, dust deposition on the mesas in our study area do not align with the expected transport consistent with modern northwesterly wind patterns. In this study, we hypothesize that anticyclonic winds from a high-pressure system above the Laurentide Ice Sheet (LIS) resulted in east to west transport and deposition of fine-grained sediment from the WRB as the Red Dog Loess. Geomorphological analysis indicated support for this hypothesis, showing significant dust deposition on the northeast edge of mesas throughout the study area. When the LIS collapsed approximately 13 ka, anticyclonic winds ended and aeolian deposition in the WRB changed to northwest wind transport, consistent with the modern wind regime seen throughout the northern WRB. Understanding the contributions of dust to climatic transitions is critical for constraining the response of terrestrial systems to climate change, and predicting future climate dynamics.