Medieval Climatic Anomaly and Mega Droughts on the Northern Great Plains

Grant Winners

Dean

Abstract

The goal of this project is to determine the timing of a major prehistoric drought that occurred in the Badlands National Park and adjacent Buffalo Gap National Grasslands, South Dakota, Northern Great Plains. We believe the Medieval Climatic Anomaly (MCA), a period of anomalously warm climate in Europe between 950 and 1250 AD, was a period of anomalously dry climate in North America, causing a drought of greater length and severity (megadrought) than any in the recorded history of the Northern Great Plains. While this megadrought predates written records, we believe it left its mark on the prairie landscape as deeply incised alluvial stream channels, wind-blown (aeolian) sand sheets, and sand dunes.

Our previous work focused on the timing of alluvial incision in the field area, which we interpreted to result from drought conditions. New here is the focus on sand dune formation in the field area, which we believe is definitive of drought conditions. Our methodology will be to collect samples for age-dating from 10 sand dune crests in two dune fields in the study area. We will use the optically stimulated luminescence (OSL) dating technique to determine the approximate time since the sand grains were buried, constraining the timing of sand dune activity.

This proposal is a revision of an American Chemical Society Petroleum Research Fund proposal submitted in 2014. Although we did not receive funding, panel feedback assured us this research track is relevant, that external funding is possible, and our results would be publishable in peer-reviewed journals. Ages of dune field sediments would offer significant constraint on climate models for the Great Plains, as well as contributing to our understanding of the natural history of an important national park.