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A review of published literature and satellite imagery from the late 1960s onwards has revealed 90 surge-type glaciers in the Karakoram mountains, of which 50 have not previously been described in detail. These glaciers were identified by a number of surface features indicative of surge-type behavior such as looped moraines, rapid terminus advance, strandlines and rapid changes in surface crevassing. These observations indicate that surge-type behavior is more common and widespread than previously believed on Karakoram glaciers. There is strong spatial clustering of the surge-type glaciers, and a doubling in the number of new surges in the 14 years after 1990 (26 surges) than in the 14 years before 1990 (13 surges). This is coincident with a period of increased precipitation and positive glacier mass balance in this region, and supports previous studies which have found that mass balance has an important control on the frequency of glacier surging. [ABSTRACT FROM AUTHOR]

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Abstract: Basin-wide rockwall retreat rates are estimated using cosmogenic 10Be concentrations in supraglacial debris from the Baltoro Glacier basin in K2 region of the Central Karakoram, Pakistan. Total cosmogenic 10Be concentrations of the supraglacial debris were measured using accelerator mass spectrometry to determine 10Be concentrations inherited from the rockwalls within the glaciated basin. Given that rockfall induced by periglacial weathering and snow and ice avalanches is the most important source of supraglacial debris production in the high mountain glaciated basin, the erosion rate of the bare bedrock can be considered to be the rate of rockwall retreat. The rate of the rockwall erosion, converted from the calculated inheritance of 10Be concentrations, using the maximum velocity of the active glacier, places an upper limit ranging from 0.65 mm/year to 2.48 mm/year. This rate of rockwall retreat is in the same order of magnitude reported in other high Himalayan mountains. The rate, however, is an order of magnitude higher than erosion rates inferred from sediment budget studies and half that of the fluvial incision rate and exhumation rate for the same region. The difference between rates of basin-wide rockwall retreat and fluvial incision rates over the Late Quaternary suggests that in this glaciated basin fluvial incision is likely enhanced by localized/differential tectonism and/or isostatic uplift. [Copyright &y& Elsevier]

Abstract: The Central Karakoram, which includes K2 in Pakistan, is one of the most rapidly rising areas on Earth and exhibits complex topography and extreme relief. Impressive valley fills and glacial landforms are present throughout the valleys. The dynamics of landscape evolution of the region are currently not well understood. Consequently, the landforms were mapped and assessed in the Skardu, Shigar, and Braldu valleys, to elucidate the spatio-temporal scale dependencies of surface processes active in the region. These valleys were examined using geomorphic field methods, remote sensing, geomorphometry, and terrestrial cosmogenic nuclides (TCNs) surface exposure dating. The glaciers in this region have oscillated considerably throughout the Late Quaternary, and four glacial stages have been recognized including at least six glacial advances. Surface processes readjusted after glacier retreat, and ubiquitous mass movements and catastrophic landsliding transported material from steep slopes to valley bottoms, while glaciofluvial meltwater and glacier outburst floods redistributed sediment down valley. Glacier geochronology and late Holocene ages of the outburst flood deposits indicate that landscape evolution has been dominated by glaciation and paraglaciation during the late Quaternary. [Copyright &y& Elsevier]