LANDSCAPE RESPONSE TO BIOCLIMATIC CHANGE ALONG THE SOUTHERN MARGIN OF THE PRAIRIE PENINSULA

Stratigraphic investigation of Bear Creek, a fourth order tributary to the Sac River in southwestern Missouri, shed light on how the landscape along the prairie-forest ecotone responds to Holocene climate and vegetation change. The chronology, lithology, and morphology of valley fill sequences were reconstructed from outcrops and from cores along several valley transects. A detailed radiocarbon chronology of the fluvial sequence defines several periods of aggradation, stability, and erosion that are similar to those found in the Sac Valley and along the Pomme de Terre valley 20 km to the east. Changes in flood frequency and magnitude interpreted from grain-size trends and point bar dimensions were combined with geomorphic data from the floodplain transects to provide a record of Holocene fluvial system behavior. Results indicate that changes in stream behavior are part of a complex response of the fluvial system to hydrologic and vegetation changes brought about by shifts in atmospheric circulation patterns during the Holocene. This analysis is a first step in understanding the complexity of the regional landscape response to bioclimatic change, and how the distribution and abundance of the region’s archaeological record is conditioned by environmental change. This information also forms a strong foundation for understanding how anthropogenic perturbations may impact this agriculturally important landscape.