Mass movement in the Himalaya: new insights and research directions

Ongoing studies that relate tectonics to the processes at the surface of Ea rth show that many more sources of information about agents of shallow denu dation, such as mass movement, are required to comprehend the long term ero sion that leads to deep denudation over geologic time. Mass movement in the Himalaya is scale-dependent, from the massive extension of whole mountain ranges (gravity tectonics), through the sackung failure of single peaks, to the smallest slope failures. Generally, denudation of the Himalayan orogen begins with slope failure onto glaciers and into river valleys and continu es by glacial and fluvial transport. The maximum size of stable slopes and mean angles of slope that are produced by these failures are complex and co ntrolled by a variety of factors, including mass strength of the rocks, str ess fields, angles of internal friction controlled by rock type, cohesion t hat includes the control of rock temperature, bulk unit weight of rock, and discontinuities. The processes of mass movement in the Himalaya have been described many times for the past two centuries. Recently, developments in a variety of fields have been introduced to assess the character of mass mo vement. Geomorphometry, remote sensing, digital elevation models, and geogr aphic information system technology are revolutionizing the study of mass m ovement in the Himalaya. (C) 1998 Published by Elsevier Science B.V. All ri ghts reserved.