Major dune construction during the Younger Dryas chronozone within the Kankakee River Valley, Great Lakes region, USA: Visible landscape response to rapid climate change

Abstract

The southern side of the Kankakee River Valley in Illinois and Indiana features an eolain landscape comprising dunes and sand sheets. These dunes are mostly parabolic in shape, ranging in height from 4 to 7 m, occasionally reaching up to 15 m. Due to limited natural exposures and fresh road cuts, three dunes were accessed for sampling through hand auguring for optically stimulated luminescence dating. To enhance our understanding of the subsurface stratigraphy, ground penetrating radar (GPR) surveys were conducted, the results of which revealed that the age variations obtained were consistent with changes from both GPR imagery and field observations. All three sampled sites indicated ages within the Younger Dryas chronozone (YDC, 12.8–11.7 ka). Notably, site KKK1 exhibited about 7 m of eolian sand, with five ages falling within the YDC. This construction of dunes during the YDC coincides with the majority of dune fields in the Great Lakes region, suggesting that the rapid climatic changes during the YDC played a crucial role in the observed dune construction here and the wider Great Lakes region. The regional consistency implies a prevailing dry climate during the YDC. While most previous YDC records are based on proxy data such as fossil pollen and stable isotope data, this study provides a tangible example of visible landscape response, construction of sand dunes, to the rapid climatic change occurring during the YDC.