Megadroughts and Late Holocene Dune Activation at the Eastern Margin of the Great Plains, North-Central Kansas, USA

 

Paul Hansen, Alan F. Arbogast, and William C. Johnson

 

          Optical dating indicates that terrace-fill alluvium underlying dunes near Abilene in east-central Kansas was deposited at ~ 45 ka, and that the overlying dunes were active ~ 1.1-0.5 ka, during a megadrought that extended across the Great Plains. Geochemical data indicate that the dune sand was sourced from the underlying alluvium. The dune-activation interval is similar to those derived from other dunes in the Great Plains, including the Nebraska Sand Hills, those near Duncan, Nebraska, and in the Cimarron Valley of Oklahoma. Although this study demonstrates that the 1.2-0.5 ka megadrought also impacted the Abilene area, the Abilene dunes do not present evidence for multiple drought events in the Holocene unlike these other dune fields. If it is not a result of sampling or preservation bias, the less frequent dune activity identified at Abilene possibly represents a difference in the extent and severity of older drought events at the margin of the Great Plains.

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