Three sand units are recognized on the basis of bedforms, topographic expression, and soil development. Preliminary age limits for the three units, based on 26 numerical ages, are 22.5-9 ka, 8-1 ka, and 1.0-0.15 ka. The middle unit is the product of multiple episodes of eolian activity that are not yet accurately dated. Loess is widespread but thin (generally < 2.4 m). Three units - middle Pleistocene, late Pleistocene, and Holocene - are recognized on the basis of differences in soil-profile development and stratigraphic position. -from Author