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Abstract: Loess deposits in the Eastern Qinling Mountains (central China) provide a detailed archive for reconstructing the paleoenvironment during early hominin occupation. The study of the loess deposits also provides a unique opportunity to understand Pleistocene atmospheric circulation in this transitional climatic zone. However, the provenance and formation of the loess deposits were not well understood until now. In this paper, we report on new geomorphologic investigations and depositional analyses of the loess deposits. The results suggest that Gobi deserts and drylands in northern and northwestern China were one of the dust sources. These loess deposits show similar geochemical composition as the average upper crust (UCC), and may indicate that they experienced multiple sedimentary processes, with the dust being well mixed before deposition. However, the higher 87Sr/86Sr ratios (between 0.719650 and 0.721043) and extremely low ɛNd(0) values (between −11.98 and −18.97), which are different from the typical loess of the Chinese Loess Plateau, demonstrate that proximal clastic sediments that were apparently derived from the weathered Qinling orogen bedrocks, form the other important source for the loess deposits. The chemical Index of Alteration [CIA = Al2O3/(Al2O3 + CaO* + Na2O + K2O) × 100] and Chemical Proxy of Alteration [CPA = 100 × Al2O3/(Al2O3 + Na2O)], both in molar proportions show that the loess has experienced intense pedogenesis. We conclude that the loess deposit has a mixed provenance. The palaeoclimate in the Eastern Qinling Mountains remained mild in the glacial periods due to the topography and unique geographic locations, providing a suitable place for hominine occupation. [Copyright &y& Elsevier]

Abstract: This paper presents the sediment, landform and dynamic context of four avalanche-fed valley glaciers (Khumbu, Imja, Lhotse and Chukhung) in the Mount Everest (Sagarmatha) region of Nepal. All four glaciers have a mantle of debris dominated by sandy boulder-gravel that suppresses melting to an increasing degree towards the snout, leading to a progressive reduction in the overall slope of their longitudinal profile. Prominent lateral–terminal moraine complexes, also comprising sandy boulder-gravel, enclose the glaciers. These terminal moraines originally grew by accretion of multiple sedimentary facies of basal glacial and supraglacial origin, probably by folding and thrusting when the glaciers were more dynamic during the Little Ice Age. The four glaciers are in various stages of recession, and demonstrate a range of scenarios from down-wasting of the glacier tongue, through moraine-dammed lake development, to post-moraine-dam breaching. Khumbu Glacier is at the earliest stage of supraglacial pond formation and shows no sign yet of developing a major lake, although one is likely to develop behind its >250m high composite terminal moraine. Imja Glacier terminates in a substantial body of water behind a partially ice-cored moraine dam (as determined from geophysical surveys), but morphologically appears unlikely to be an immediate threat. Chukhung Glacier already has a breached moraine and a connected debris fan, and therefore no longer poses a threat. Lhotse Glacier has an inclined, free-draining tongue that precludes hazardous lake development. From the data assembled, a conceptual model, applicable to other Himalayan glaciers, is proposed to explain the development of large, lateral-terminal moraine complexes and associated potentially hazardous moraine dams. [Copyright &y& Elsevier]

Abstract: This paper presents the sediment, landform and dynamic context of four avalanche-fed valley glaciers (Khumbu, Imja, Lhotse and Chukhung) in the Mount Everest (Sagarmatha) region of Nepal. All four glaciers have a mantle of debris dominated by sandy boulder-gravel that suppresses melting to an increasing degree towards the snout, leading to a progressive reduction in the overall slope of their longitudinal profile. Prominent lateral–terminal moraine complexes, also comprising sandy bouldergravel, enclose the glaciers. These terminal moraines originally grew by accretion of multiple sedimentary facies of basal glacial and supraglacial origin, probably by folding and thrusting when the glaciers were more dynamic during the Little Ice Age. The four glaciers are in various stages of recession, and demonstrate a range of scenarios from down-wasting of the glacier tongue, through morainedammed lake development, to post-moraine-dam breaching. Khumbu Glacier is at the earliest stage of supraglacial pond formation and shows no sign yet of developing a major lake, although one is likely to develop behind its >250m high composite terminal moraine. Imja Glacier terminates in a substantial body of water behind a partially ice-cored moraine dam (as determined from geophysical surveys), but morphologically appears unlikely to be an immediate threat. Chukhung Glacier already has a breached moraine and a connected debris fan, and therefore no longer poses a threat. Lhotse Glacier has an inclined, free-draining tongue that precludes hazardous lake development. From the data assembled, a conceptual model, applicable to other Himalayan glaciers, is proposed to explain the development of large, lateral-terminal moraine complexes and associated potentially hazardous moraine dams. – 2008 Elsevier Ltd. All rights reserved. [Copyright &y& Elsevier]