Present address: German Research Center for Geosciences GFZ, Potsdam, Germany.
Cosmogenic nuclide-derived rates of diffusive and episodic erosion in the glacially sculpted upper Rhone Valley, Swiss Alps
Version of Record online: 13 JAN 2010
Copyright © 2010 John Wiley & Sons, Ltd.
Earth Surface Processes and Landforms
Volume 35, Issue 6, pages 651–662, May 2010
How to Cite
Norton, K. P., von Blanckenburg, F. and Kubik, P. W. (2010), Cosmogenic nuclide-derived rates of diffusive and episodic erosion in the glacially sculpted upper Rhone Valley, Swiss Alps. Earth Surf. Process. Landforms, 35: 651–662. doi: 10.1002/esp.1961
- Issue online: 5 MAY 2010
- Version of Record online: 13 JAN 2010
- Manuscript Accepted: 26 OCT 2009
- Manuscript Revised: 9 OCT 2009
- Manuscript Received: 11 MAR 2009
- central Swiss Alps;
- cosmogenic 10Be;
- denudation rates
Denudation rates of small tributary valleys in the upper Rhone valley of the Swiss Central Alps vary by more than an order of magnitude within a very small distance (tens of kilometers). Morphometric data indicate two distinct erosion processes operate in these steep mountain valleys. We determined the rates of these processes using cosmogenic beryllium-10 (10Be) in pooled soil and stream sediment samples. Denudation in deep, glacially scoured valleys is characterized by rapid, non-uniform processes, such as debris flows and rock falls. In these steep valleys denudation rates are 760–2100 mm kyr−1. In those basins which show minimal previous glacial modification denudation rates are low with 60–560 mm kyr−1. The denudation rate in each basin represents a binary mixture between the rapid, non-uniform processes, and soil creep. The soil production rate measured with cosmogenic 10Be in soil samples averages at 60 mm kyr−1. Mixing calculations suggest that the debris flows and rock falls are occurring at rates up to 3000–7000 mm kyr−1. These very high rates occur in the absence of baselevel lowering, since the tributaries drain into the Rhone trunk stream up-stream of a knickzone. The flux-weighted spatial average of denudation rates for the upper Rhone valley is 1400 mm kyr−1, which is similar to rock uplift rates determined in this area from leveling. The pace and location of erosion processes are determined by the oscillation between a glacial and a non-glacial state, preventing the landscape from reaching equilibrium. Copyright © 2010 John Wiley & Sons, Ltd.