Department of Geography and Environmental Studies
The investigation primarily concerns contemporary geomorphological features and processes in the Upper Indus Basin, Past work, and theories of the denudation chronology of the region are described, and the broad climatic and geological setting. The bulk of the work examines characteristics of weathering, slopes and mass-movements, glacial and fluvial features in the Biafo Gyang area of the Central Karakoram. The nature and role of glacier surges and natural damming in the region are discussed. An effort is also made to support the central theme with background information and visual illustration not normally available, and a comprehensive regional bibliography is provided.
Weathering processes show an intimate interaction of chemical decay, salt weathering, frost action and primary mechanical failure of rock, A variety of forms is produced from tafoni to exfoliation structures, while weathering products are mainly angular with little clay fraction. This seems mainly due to rapid rates of removal which preclude advanced decay. Slopes are steep, most of the Biafo Basin area exceeding 45° of angle. This, large upslope variations in climate and lack of vegetation promote vigorous mass -movements and varied slope deposits.
The Biafo Gyang Glacier is one of many enormous valley glaciers in the region, and is of the "Firn-Stream" type, The ablation zone has extensive covers of moraine and large flanking kame terraces. There is a short, vigorous melt season and marked resurgence of the glacier margins and terminus in winter.
Above the Biafo the Braldu River flows in a wide belt of valley train, but plunges into a deep gorge with huge terraces and rock walls below the glacier's entry. 80% of the Upper Indus rivers' discharge occurs in three months of the year and over 90% of the sediment transport. Extreme erosional events play an important role in the region, special significance attaching to the many natural dams and dam-burst floods. Overall, the orographic effect tends to express itself by promoting short-lived, high energy erosional events.
Hewitt, K. (1961). Studies in the geomorphology of the mountain regions of the Upper Indus basin. S.l.: S.n., 1962?].