The Role of Cap Debris Deposits on Geomorphic Sensitivity of Landscape: Slopes of North of Ghechi-Ghalasi Mountain (Northwest of Iran)

This paper aims to difine the sediment, landform and dynamic context of part of slopes near Ghechi-ghalasi stock in northern slope of Mishow-Dagh chain in northwest of Iran. The surfaces of studied slopes are mostly covered by surficial deposits that are yielded from weathered materials (mix of boulders, gravels, sand and clay) of stock and thinned by keeping away from it. These deposits significantly affect erosion rates, geomorphologic evolution, landuse and density of drainage. 19 sections were created along the Aralan rural road for the study of thicknesses of surficial deposits and quality of their rehabilitation on the lower weak Miocene formations. Results show that the residuum seems to be stable under current climate than uncovered slopes of the study area. The presence of debris deposits on Miocene sediments (mainly marly) in study area, have an inevitable role on slope stability. In spite of such importance of these debris deposits, removal of debris cover and the exposure of Miocene formations as the result of recent anthropogenic erosion and repairs (road widening and other repairing operations), caused aggravation of geomorphic processes activity such as mass wasting and gully and rill erosion. From the data gathered, a conceptual model, applicable to other similar slopes, is proposed to explain the evolution of geomorphic sensitive slopes and associated potentially hazardous slope instabilities.