Li Shude, Yao Heqin
The Gongga Mountains are located on the southeastern fringe of Qingh-ai-Xizang Plateau and in the northeast of the Heng Duan Mountains,where the climate is very complex and variable. In this area, modern glaciers arc densely developed. According to statistical data, there are 71 morden glaciers and 650 obvious avalanche chutes there here. The modern snow line is 4800-4900 m a. s. 1. on the southea-stern slope, 5000 m a. s. 1. on the northwestern slope. The 0 ℃ isotherm coincides with 4000 m isohypse. The lower limit of the alpine permafrost is 4800 m a. s. 1. on the southeastern slope, and 4600 m a. s. 1. on the northwestern slope, while the lower limit of the sporadic permafrost can be as low as descend 4200 m on the western slope. In this area, there are 24 rock glaciers with different shapes, distributed between 4200 m and 4800 m a. s. 1., 3 on the north slope, 19 on the western slope and 2 on the eastern slope. This is an area where many rock glaciers of marions types are most densely developed in our country.According to their geomorphological distribution locations, material sources, shapechar-acteristics and ground ice types, the rock glaciers can be classified into four types: pediment,valley, valley-waterfall and half-covered.Valley and valley-waterfall rock glaciers have not cracks,but also buried ground ice,and their movement is fast. The largest one is a valley rock glacier in the Zimeishan, whidh is about 3 km in length and 300 m in width, with the height of the front fringe cliff up to 50 m. Pediment and half-covered rock glaciers generally only develop crack ice by which rock glacier is solidified and have localized buried ice. Their creep mainly deperds on the gravitational action and is slow. They are smaller in size than the first two types.
