Isotopic and geomorphic evidence for Holocene Climate, Southwestern Kansas

Abstract

The Cimarron Bend of southwestern Kansas is characterized by loess, dunes, and sand sheets that reflect a complex eolian–alluvial history. Stratigraphic evidence indicates that at least two major dune and sand sheet reactivation episodes occurred. These follow intervals of alluviation, stability, and soil development in the Holocene. Radiocarbon ages from paleosol horizons bracket these periods and their δ13C values provide evidence of a shift from a cooler, wetter climate in the late Pleistocene and early Holocene dominated by C3 plants, to a warmer, drier middle Holocene period characterized by an increase in C4 plants. Stable isotopic results for late Holocene soils may reflect local rather than regional climatic conditions. Our results compare favorably with studies in the central and southern Great Plains. Together, these results imply that a regional change toward a warmer, drier climate occurred from the early to the middle Holocene on the southern Great Plains.