Glaciers and mass wasting processes: their influence on the shaping of the Kali Gandaki valley (higher Himalaya of Nepal)

This paper addresses the question of the respective role of glaciers and mass-wasting processes in the shaping of the high valleys of the Central Himalaya. This is a region in which the Himalayan range is at its narrowest and where it is cut by the deepest gorge in the world (the Kali Gandaki valley). Following a brief description of the region and of the criteria used to discriminate between both sets of processes, some specific sites that have given rise to divergent interpretations are discussed. It is shown that undoubted evidence of past glaciation is rare and that most of the diamictons observed today are best interpreted as the products of deep-seated landslides and/or catastrophic debris flows of large magnitude and probably low frequency (spanning the period from the Last Glacial Maximum to the Holocene). The modalities of this evolution cast some doubt on some former reconstructions of past glacial extents. Moreover, the continuous reworking of this material continues to influence the nature and current rates of erosion. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved.