Rockwall slope erosion of mountain catchment headwaters

The aim of this project was to evaluate the contribution of rockwall slope erosion to the denudation budgets of glacierized alpine catchments. The first step of this project was to identify the principal mechanisms of rockwall slope erosion and evaluate the feasibility of using cosmogenic nuclides in supraglacial sediment to quantify this erosion. This study demonstrated the importance of periglacial rockfall processes within rockwall slope erosion, catchment divide migration and mountain range evolution of the Garhwal Himalaya (Orr et al., 2019). This study modelled cosmogenic nuclide accumulation in sediment moving through the glacier system and provided a unique insight into how erosional processes operate within a glaciated setting. A further aim of this study has been to resolve the drivers of rockwall slope erosion by comparing erosion of catchment headwaters across gradients in lithology, topography, rock uplift, and climate in the northwestern Himalaya (Orr et al., accepted). This project has shown that tectonically driven uplift, rather than climate, provides a first order control on patterns of rockwall slope erosion. The wider significance of this project is that we show that patterns of late Quaternary erosion are closely associated with denudation records from the Oligocene to the Pliocene. Tectonically driven uplift has therefore moderated the pace of landscape evolution since the formation of the orogen. This research has been funded by the Geological Society of America (GSA), National Geographic and PRIME laboratories, Purdue University, and has been presented at regional and annual GSA and American Geophysical Union meetings, and the 6th Third Pole Environment workshop.

Orr, E. N., Owen, L.A., Caffee, M., (2019). Rates of rockwall slope erosion of the upper Bhagirathi catchment, Garhwal, northern India. Special Issue: ‘Geomorphic diversity of the Indian sub-continent: Progress and Updates. Earth Surface Processes and Landforms. 44, 15, 3108-3127. https://doi.org/10.1002/esp.4720

Orr, E.N., Owen, L.A., Saha, S., Hammer, S.J., Caffee, M.W., (accepted). Rockwall slope erosion of the northwestern Himalaya. Journal of Geophysical Research: Earth Surface.