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This study aims at quantifying the influence of glacial erosion on the large-scale hypsometry of mountain ranges. We take a global approach and analyse digital elevation models (DEM's) from a range of dominantly fluvial and dominantly glaciated or previously glaciated areas, in search for distinct differences in hypsometric expression between the two. Observations from the Cascade Ranges (Mitchell and Montgomery, 2006) indicate that long-term glacier equilibrium line altitudes (ELA) provide an important control on topography. This 'glacial buzzsaw effect' exhibits concentrated erosion near peaks and is demonstrated in a distinct spatial relationship between maximum altitude and the ELA, and is seen to produce a gently sloping summit envelope with a limiting height related to the ELA.
Furthermore, computational surface process models also point towards glacial erosion focused near the peaks (Tomkin and Braun, 2002), indicating that the height distribution could be controlled by glacial erosion processes and to some degree be explained by established ideas on subglacial conditions related to basal sliding. We find general patterns in the hypsometric distribution of mountain areas. Fluvial areas exhibit the well-known exponential decrease of area with height, whereas areas influenced by glacial erosion seem to exhibit an accumulation of area in a certain height interval, well above the average height of the landscape surrounding the topography. For purely fluvial landscapes this accumulation of area is absent. Furthermore, we find that the area which is over-represented has a lower topographic slope than the surroundings. The accumulation of area for a given height in the glacial landscapes can be recognised as summit envelopes related to an ELA or a former ELA in the area.
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