Investigating Sediment Source to Sink Processes in a Post-Orogenic Landscape

In order to understand the life cycle of a mountain range, it is crucial to identify and quantify the processes that influence the rate of denudation, sediment flux through the landscape, and the resulting changes in relief over long time scales in tectonically-inactive regions. The timescales of these geomorphic processes and the quartz-rich lithologies make the southern Appalachian Mountains an ideal location for terrestrial cosmogenic nuclide (TCN) measurements aimed at studying erosion and denudation processes in an evolving post-orogenic landscape. We used in situ-produced TCN measurements of ¹⁰Be to determine the denudation rate in 10 catchments along the southern Appalachians. The locations selected are all within the east-draining Blue Ridge escarpment in North Carolina and Georgia. In 5 of the 10 catchments we sampled two grain sizes, gravel and sand. Our analysis provided erosion rates of 15 to 26 mm Ky^-1 for the 0.025 to 0.050 cm sand samples and 12 to 20 mm Ky^-1 for 3 to 8 cm gravel. We analyzed these TCN measurements in the context of several basin metrics, including slope and relief, derived from a digital elevation model (DEM). Our results provide additional evidence that denudation rates are difficult to estimate with DEM-calculated basin metrics in the southern Appalachians.