Playa-Lunette Systems and Paleoenvironmental Change on the Central High Plains

Reconstructing landscape response to past climate change is essential for predicting response to future change. Playas - small, ephemeral lakes found throughout the High Plains - represent a record of environmental change as far back as late Pleistocene. Dune-like accumulations, termed lunettes, form from material deflated from playas during extended dry periods and also represent a prolonged history of landscape change.

Goals of this research are to reconstruct regional paleoclimate, determine playa/landscape response to climate change, and determine primary processes of playa evolution. To accomplish this, several playas with lunettes were investigated in western Kansas to document and correlate stratigraphic units in and around these playa-lunette systems. Soil cores were collected from playas and lunettes using a coring machine. Examination of soil cores indicates that four or more well-developed and several incipient buried soils are common within lunettes, while two or more buried soils are common within the playa.

Soil cores have been sampled and analyzed for particle size distribution, stable carbon isotope composition, and magnetic susceptibility. Buried soils were radiocarbon dated to develop numerical age control and models for soil formation and depositional events. Stable carbon isotopes were used to infer paleovegetation, paleohydrology, and paleoclimate. The emerging chronology, extracted from within these playa-lunette systems, indicates a prolonged history of environmental change, pre-dating 40,000 yr BP. Stable carbon isotope and radiocarbon data indicate changes in the prevailing plant community composition coeval with times of global climate change, such as MIS 3 and the Younger Dryas, as well as regionally expressed climate changes. From data currently available, it is obvious that a complex and extensive history of soil formation and landscape change is recorded within playas and lunettes of the High Plains. These soils also record shifts in dominant vegetation type, indicating climate has been variable throughout the history of playa evolution.