Sand wedges, formed mainly in a Late Pleistocene alluvial gravel in the Hexi Corridor are described in detail in this paper. C-14 ages of the infilling eolian sand indicate that the sand wedges were products of the Last Ice Age. During the period of formation, the mean annual air temperature in the Hexi Corridor was about - 5.3 degreesC, i.e. 12.6-14.6 degreesC lower than that of the present day. This estimated value is coincident with the fall in mean air temperature of 13 degreesC, which is predicated from a mirabilite (Na2SO4.10H(2)O) sedimentary layer, and also agrees with research on the estimated amplitude of air temperature lowering in middle and high latitudes of the Northern Hemisphere during the last glacial,period. The annual precipitation in the Western Hexi Corridor at that time was probably 100-200 mm, about 100 mm more than at present. (C) 2002 Elsevier Science B.V All rights reserved.
