Sedimentary and tectonic controls on strath terrace formation in bedrock channels

Braudrick Christian A, Berkeley CA

Investigators

Abstract

Dr. Christian Braudrick has been granted an NSF Earth Sciences postdoctoral fellowship to be implemented at the University of California Santa Cruz. This study will use laboratory river channels to explore how changes in climate and tectonic uplift rate alter the formation of bedrock river terraces. He will test the relative importance of these two hypotheses using a sinuous laboratory channel that is able to erode both laterally and vertically. A series of experiments will investigate how bedrock terrace occurrence and morphology reflects changes in sediment supply, base level fall, and whether strath terraces arise under constant boundary conditions. These experiments will also provide a robust dataset linking sediment supply, flow hydraulics, and sediment cover in meandering bedrock channels that can be used to test and develop numerical models of bedrock river erosion. Bedrock river terraces form when channel incision decreases and lateral erosion dominates vertical erosion. They are widespread features in tectonically active areas and are often used to infer tectonic and/or climate history, but isolating the role of climate versus tectonics has proven difficult. The study will introduce an undergraduate student interested in academic research to conduct experiments and analyze how changes in sediment supply affect the amount of the bed covered by sediment. We will also incorporate a one-day field trip to the laboratory facility as part of the geomorphology class at UC Santa Cruz and provide a field trip for land managers interested in the evolution of streams in the Central California Coast, many of which are lined by bedrock terraces.