Paleoglacial Traces and Series of Mutiglaciation in the Luojieshan Mountain
Cui Zhijiu Xie Youyu and Li Hongyun ( Dept of Geography, Beijing University, "Institute of Geography. Academia Sinica. Sichuan Pan Xi Geological Brigade Team)
In the Luojieshan mountain, there are four series of paleogfacial traces indicating the corresponding mutiglaciations, i.e. the oldest one-Bamudi Ice Age, the older Luojieshan Ice Age; the younger - Dahaizi Ice Age; and the youngest one neoglaciation or Zhiluoda Ice Age. They are corresponding to the Minder, Riss, Wurm and Neoglaciation respec - tively. Cirques, trough valleys, moraines and nettles on the original flat top of the northern Luojieshan near the Bamudi highland (4200m) were formed during the Bamudi Ice Age, characterized by small ice caps with small glacial tongues. Afterward, it followed by the Baibaiding 'interglacial period. During such a long period, the erosion was so strong that landforms were changed considerably. During the next glaciation the Luojieshan Ice Age, some deeper and wider trough valleys and lager moraines were well-developed. The overflow valley glaciers extended as long as 10km or more and their teminus went down to an elevation of 2500m. The glacial landforms were not changed too much during the Qingshuiguo interglacial period. In the Dahaizi !ce Age landforms formed by glacial erosion, such as troughs, cirque lakes, glacial erosion lakes, glacial bosses, roche moutonnee and subglacial channels, were well-developed and well pressrued. Especially, the numerous and large grooves, typical in form, should be the exceptional features there. There are lots of crescentic cracks in those grooves, some of them tilt downward the valley, others tilt upstream. But they are all located at the wall foot of trough valley.