Tectonic control on the persistence of glacially sculpted topography.
One of the most fundamental insights for understanding how landscapes evolve is based on determining the extent to which topography was shaped by glaciers or by rivers. More than 10(4) years after the last major glaciation the topography of mountain ranges worldwide remains dominated by characteristic glacial landforms such as U-shaped valleys, but an understanding of the persistence of such landforms is lacking. Here we use digital topographic data to analyse valley shapes at sites worldwide to demonstrate that the persistence of U-shaped valleys is controlled by the erosional response to tectonic forcing. Our findings indicate that glacial topography in Earth's most rapidly uplifting mountain ranges is rapidly replaced by fluvial topography and hence valley forms do not reflect the cumulative action of multiple glacial periods, implying that the classic physiographic signature of glaciated landscapes is best expressed in, and indeed limited by, the extent of relatively low-uplift terrain.
Department of Geoinformatics, University of Salzburg, Hellbrunnerstraße 34, Salzburg 5020, Austria.
Günther
G
Prasicek
Division of Geological and Planetary Sciences, California Institute of Technology, MC-170-25, Pasadena, California 91125, USA.
Isaac J
IJ
Larsen
Department of Earth and Space Sciences, University of Washington, Johnson Hall, 4000 15th Avenue NE, Seattle, Washington 98195, USA.
David R
DR
Montgomery