Abstract The possible role of paraglacial adjustments in catastrophic rock-slope failures is investigated. Most of some 250 rockslide–rock-avalanche events identified in the Upper Indus Basin descended from slopes affected by Quaternary glaciations. Examples from the lower Gilgit Basin in the Karakoram Himalaya illustrate relations of rock-wall failure to former glacier activity and post-glacial responses, including sackung features. In many cases there is strong morphological evidence for paraglacial adjustments. However, other conditions must be considered as partial or alternative controls. They include a complex bedrock geology and seismo-tectonic conditions, and vertical shifts in periglacial and moisture climates. Given the enormous relief, the landslides themselves may involve a range of temporal and spatial distributions influenced by different topo-climates, geological terranes and stages of deglaciation. Meanwhile, post-glacial rock avalanche barriers have blocked and fragmented the river system. They exercise a major control over intermontane sedimentation and valley morphology. These impacts are treated as part of a broader ‘disturbance-regime’ geomorphology, where late Quaternary landscape evolution is driven by transient, but recurring, interactions among geomorphic process systems. Post-glacial conditions have also tended to partition the landscape into subunits with different mixes of geomorphic activity or rates of adjustment. The findings presented here depart from existing interpretations of Quaternary events in the region, and pose challenges for process geomorphology and the role of large landslides.

Thick deposits preserved in deep valleys in the Indus, Gilgit, and Hunza River Basins, and a variety of dates, allow new definition of Quaternary events in the Karakoram and Nanga Parbat Himalaya. An unusually long record for an actively eroding high mountain area is recognized in three major episodes of glaciation during Pleistocene time. An early glaciation is represented by the indurated lower Jalipur tillites and heterogeneous upper Jalipur valley-fill sedimentary rock younger than 1 to 2 Ma, which are folded, overturned, or overridden by rapid movement on the dextral-reverse Raikot fault. This is associated with high overall uplift rates of the Nanga Parbat–Haramosh massif during late Cenozoic time. The middle glaciation is represented by two tills intercalated within variable sediments, including thick lacustrine units dipping as much as 43° along the fault. The Indus-Shatial till of the early middle glaciation records the farthest advance of Pleistocene glaciers down the Indus River valley. The last glaciation apparently occurred after about 140,000 yr ago and consists of three to four or more separate advances, as recorded by morainic topography. The most prominent of these is the Dianyor moraine near Gilgit, which was produced by a major longitudinal glacier. Near Haramosh and downstream at Nanga Parbat, Shatial, and elsewhere, transverse glaciers blocked the Indus River to produce lake deposits now dipping as much as 6° near the fault. Catastrophic floods from failure of the ice dams, and possibly landslide dams as well, emplaced some Punjab erratics and sediments that may have been reworked into loesses and other sediments at the mountain front.