贡巴冰川边缘冰碛垄特征与形成过程

The Characteristics and Forming Process of Glacial Peripheral Moraines at Gongba Glaciers in Mt. Gongga

Based on the field observations to the glacial peripheral moraines at Gongba Glaciers in Mt. Gongga, there are differences in shapes between the younger moraines and the older ones, there are also differences at different spost. The inner-slope of lateral moraine is much steeper than the out-slope, and is pressed and abrased by the glacier.The debris becomes from less sharp to less round, in the cross sections of the lateral moraine, the debris is parallel to the out-slope surface. The grain-size analysing data show that in the inner-slope of the lateral moraine the grain-size is smaller than the out-slope, but the degree of sorting of the inner-slope is poorer than the out-slope. At the margin of glacier, the force of glacier to lateral moraine can be separated into three components, they related to the components of the velocity at the ablation area. The forces can be combined into an acting force parallel- to the lateral moraine and an acting force vertical to the moraine. The fore has a "pruning acting" to the moraine, the later forms shear plan between glacier and lateral moraine. The debris can be brought to the superglacial surface from sub-or in -glacial places, and then slips or falls on the out-slope of the moraine under the gravity. In this way , the lateral moraine is made up. In this area, there are similar characteristics and forming process between end moraine and lateral moraine.