6o8 ELLSWORTH HUNTINGTON 



tion lies first in the oversteepened lower slopes of the mountains 

 already referred to in describing the appearance of the lake, and 

 second in numerous erratic bowlders of granite perched on slopes 

 and ridges of schist or of metamorphic sedimentary rocks (Fig. 9). 

 The bowlders vary in size from i to 25 feet in diameter, and are 

 found at all elevations up to at least 600 feet above the lake. They 

 occur on both sides of the latter, and on almost every slope facing 

 toward it or toward the outlet. The greatest accumulations are 

 found in small protected valleys such as those marked A, B, and C 

 on the map. The granite bowlders can have been brought to their 

 present position on the schist only by a glacier large enough to fill 

 the whole Pangong basin. 



The glacier did not come to an end at the rock-hp, as might be 

 expected, but, as we have already seen, continued on for 20 or 

 30 miles as a comparatively narrow tongue giving rise to the U -shape 

 of the outlet valley, and to the glacial knobs already described, and 

 leaving at least one hanging valley with its mouth 200 feet above the 

 flat valley floor on the south side near the httle lake of Tso Tsear. If 

 the Pangong basin is due to glacial erosion, it is necessary to explain 

 why in what once was a single uniform valley the part above the lip 

 has been widened ten times as much as the part below, and deepened 

 correspondingly. Rock structure and texture have something to 

 do with the matter, for there is a hard stratum of marble at the lip; 

 but, except for this, the difference between the schists and meta- 

 morphic sedimentaries above and below the hp seem insufficient 

 to account for so marked a contrast. It is possible that the Lukung 

 glacier from the north meeting the Pangong glacier from the south- 

 east acted as a check upon the latter, causing it to broaden and 

 deepen its channel up-stream instead of down. Another possibility 

 is that a glacier or glaciers of smaller size previous to the maximum 

 glacier may have reached only to the lip, broadening the valley 

 above, but not below. When the maximum glacier advanced, the 

 constriction of the valley at the lip would allow only a narrow tongue 

 to extend forward and would cause broadening and deepening of 

 the channel upward. 



There is still doubt as to the possibility of the excavation of basins 

 by glaciers. The Pangong basin offers nothing new by which the 



