Late Holocene dune accretion and episodes of persistent drought in the Great Plains of Northeastern Colorado

The Great Plains of the Mid West USA contain dunefields which display stratigraphic evidence of episodic sand drift throughout the Holocene and, in some cases, the Late Pleistocene. Widespread aeolian activity has been linked to persistent megadroughts caused by a weakening of the tropical moisture-laden circulation from the Gulf of Mexico and equatorial Pacific. Infrared stimulated luminescence (IRSL) dating has been applied to two exposures in the Fort Morgan dunefield of northeastern Colorado where radiocarbon-dated buried soils provide ages for land surface stability. IRSL ages show that sand drift occurred episodically during the Late Holocene at 4.85, 2.37, 1.06, 0.80, 0.6-0.53 and 0.37 ka. (C) 2003 Elsevier Science Ltd. All rights reserved.