YOUNG QUATERNARY SLOPE SEDIMENTS AND PALEOSOILS IN THE COLORADO FRONT RANGE - PROCESS AND AGE

The subalpine to montane zones of the Colorado Front Range, U.S.A. are characterized by the abun­dance of stratified slope deposits exhibiting depths > 1 m and recurring sediment characteristics within the respective strata complexes. Apart from the initial description by Leopold et al. (2008a), they have not been investigated up to now in terms of either their genesis or age. First OSL dating attempts demonstrate the general applicability of the dating method in this context and render last glacial ages ranging between 40 and 12 ka. Across a landscape transect stretching W-E from the subalpine zone east of the Continental Divide (tree line at Niwot Ridge) to the zone of the Foot Hills at the border with the Great Plains (Boulder), representative profiles are investigated with regards to hypsometric dif­ferences in stratification, sediment characteristics and morphodynamics. Most notably the montane zone of the Colorado Front Range is characterized by a lack of a considerable number of paleoclimatically interpretable geoar­chives due to its semiarid climatic conditions. Additionally the slope sediments provide a basis for dis­cussing the position of the permafrost line during the LGM. Therefore the state of the art project contributes a novel approach to the reconstruction of paleoenvironments and paleoclimates across the various altitudinal zones of the Colorado Front Range.