Great Plains Midcontinental Loess Deposits Following Prehistoric Megadroughts and Climate-Change Related Ecosystem Collapse in the Badlands
Abstract
Understanding effects of prehistoric extreme climate events on the environment is necessary to help predict effects of modern global climate change. Research shows prehistoric megadroughts caused the collapse of North American grassland ecosystems, allowing wind to erode soils and fined-grained sediment. Timing, severity, and regional extent of these megadroughts remain controversial, but research indicates at least three megadrought periods on the North American midcontinent over the last 20,000 years. Evidence for prehistoric megadroughts is preserved in dune fields and loess deposits throughout the North American Great Plains, including our field area in the Badlands of South Dakota. Loess, composed of very fine sand and silt, forms important midcontinental agricultural deposits in Nebraska and Iowa. The goal of this study is to determine whether fine-grained Badlands sediments are a source of the midcontinental loess. In this study, we analyzed particle size distribution and geochemical composition of sediments from the Badlands and compared these results to loess composition in southern Nebraska and Iowa. Results show compositional similarities between dune sands and river deposits from the Badlands and the midcontinental loess. Results support the hypothesis that links Badlands dune formation with midcontinent loess formation, implying widespread ecological collapse in the past and the potential for another collapse in the future. We believe these climate disasters are linked to global climate events such as the last glacial maximum, medieval climate anomaly, and the Little Ice Age. Reactivation phenomenon could trigger the onset of catastrophic climate-related events across the Great Plains.
Faculty Sponsors
Dr. Paul Baldauf
Project Type
Event
Location
Alvin Sherman Library
Start Date
4-6-2022 12:00 PM
End Date
4-7-2022 5:00 PM
Great Plains Midcontinental Loess Deposits Following Prehistoric Megadroughts and Climate-Change Related Ecosystem Collapse in the Badlands
Alvin Sherman Library
Understanding effects of prehistoric extreme climate events on the environment is necessary to help predict effects of modern global climate change. Research shows prehistoric megadroughts caused the collapse of North American grassland ecosystems, allowing wind to erode soils and fined-grained sediment. Timing, severity, and regional extent of these megadroughts remain controversial, but research indicates at least three megadrought periods on the North American midcontinent over the last 20,000 years. Evidence for prehistoric megadroughts is preserved in dune fields and loess deposits throughout the North American Great Plains, including our field area in the Badlands of South Dakota. Loess, composed of very fine sand and silt, forms important midcontinental agricultural deposits in Nebraska and Iowa. The goal of this study is to determine whether fine-grained Badlands sediments are a source of the midcontinental loess. In this study, we analyzed particle size distribution and geochemical composition of sediments from the Badlands and compared these results to loess composition in southern Nebraska and Iowa. Results show compositional similarities between dune sands and river deposits from the Badlands and the midcontinental loess. Results support the hypothesis that links Badlands dune formation with midcontinent loess formation, implying widespread ecological collapse in the past and the potential for another collapse in the future. We believe these climate disasters are linked to global climate events such as the last glacial maximum, medieval climate anomaly, and the Little Ice Age. Reactivation phenomenon could trigger the onset of catastrophic climate-related events across the Great Plains.
