Middle Holocene aeolian activity on the High Plains of west-central Kansas

Abstract

The uppermost surficial stratigraphic unit south of the Arkansas River in the Kansas High Plains is a previously unidentified middle Holocene or younger loess. The unit fits both a loess-thickness and a particle- size model for loess distribution with increasing distance from source. A soil immediately below this unit is radiocarbon dated 6000 to 6700 years BP. The radiocarbon ages indicate that the loess unit is younger than the commonly reported ranges for Bignell Loess in the Great Plains and demonstrate a need for re-examining Holocene loess stratigraphy of the Great Plains. In some locations closest to the Arkansas valley source, this middle Holocene unit is overlain by, or interfingers with, dune sands. The presence of these aeolian sands indicates that, following a period of relative landscape stability and soil development, a shift toward a middle- Holocene climate in which aeolian processes dominated occurred about 6000 years ago on the High Plains of west-central Kansas.