Abrupt glacial valley incision at 0.8 Ma dated from cave deposits in Switzerland
- 1Institute of Applied Geology, University of Natural Resources and Applied Life Sciences, Peter Jordan Strasse 70, 1190 Vienna, Austria
- 2Earth and Atmospheric Sciences, 1397 Civil Engineering Building, Purdue University, West Lafayette, Indiana 47907, USA
- 3Swiss Institute for Speleology and Karstology SISKA, Box 818, 2300 La Chaux-de-Fonds, Switzerland
- 4Department of Earth Science, University of Bergen, Allegaten 41, 5020 Bergen, Norway
Abstract
Glacial erosion dramatically alters mountain landscapes, but the pace at which glaciers carve a previously fluvial landscape remains poorly defined because long-term valley incision rates are difficult to measure. Here we reconstruct the lowering history of the Aare Valley, Switzerland, over the past 4 m.y. by dating cave sediments with cosmogenic 26Al and 10Be. Incision accelerated from ∼120 m/m.y. to ∼1200 m/m.y. at 0.8–1.0 Ma, at least 1 m.y. after the onset of local glaciation. Rapid incision may have been triggered by lowering of the equilibrium line altitude at the mid-Pleistocene climate transition.
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- Received 14 June 2006.
- Accepted 25 September 2006.
- Revision received 12 September 2006.
- Geological Society of America
