本帖最后由 细胞海洋 于 2013-1-11 22:06 编辑 5 t! a! ^$ q/ r0 b % A1 J3 d" q. @% v# c w1 D) ~* v3 X! V$ S6 i3 l1 o
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Large parts of the Earth’s surface were glaciated during the Quaternary cold periods of the past 2.5 million years, and these events have left their mark on the mountain topography we see today. Post-glacial landscapes tend to feature large areas concentrated at the same elevation, but the effect of this on subsequent glaciations was unknown. Vivi Pedersen and David Egholm use numerical simulation of glaciation and case studies of alpine topography of the Sierra Nevada, Spain, where there was little glacial activity in the Quaternary, and the Bitterroot Range in Idaho, which was significantly modified by glaciers during the Quaternary. The results show that prior glaciations transform a system from one in which climate exerts a near-linear influence on glacial extent to one in which a small change in climate can result in massive glacial expansion. This helps to explain the long-term patterns of erosion in the Quaternary period. (Cover image: Nicolaj Krog Larsen, Aarhus University.)* ]9 w) n* B6 v B7 F7 l/ M" p
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