REMOVAL AND TRANSPORT OF SANDSTONE CAPROCK MATERIAL AS A RATE-LIMITING STEP IN LANDSCAPE EVOLUTION, BUFFALO RIVER BASIN, AR

Most bedrock channel studies are set in areas of active tectonism. Within this setting it is generally assumed that channel morphology is dependent on rock strength, stream power, and uplift rates. The Buffalo National River of northwestern Arkansas sits on the Ozark Plateau which is a tectonically passive setting. Upper reaches of tributary streams of the Buffalo River are often surrounded by ridges capped by a cliff-forming Pennsylvanian sandstone. These cliffs release large blocks that migrate downslope, eventually reaching tributary streams. Previous work within the basin showed that normalized channel steepness correlates with percent boulder coverage and boulder size rather than lithology. This suggests that removal of caprock material is rate-limiting within the landscape and may be responsible for long term persistence of topography. Here we investigate the processes of cliff retreat and migration of caprock material down hillslopes and examine how these processes influence long term landscape evolution.