248 EAST NEPAL. Chap. X. 



temperature was 37^°. The black bulb thermometer rose 

 on one occasion 84° above the surrounding air. Before 

 leaving, I measured by angles and a base-line the elevations 

 of the great village-terrace above the river, and that of a 

 loftier one, on the west flank of the main valley ; the 

 former was about 400 and the latter 700 feet. 



Considering this latter as the upper terrace, and con- 

 cluding that it marks a water level, it is not very difficult 

 to account for its origin. There is every reason to suppose 

 that the flanks of the valley were once covered to the ele- 

 vation of the upper terrace, with an enormous accumulation 

 of debris ; though it does not follow that the whole valley 

 was filled by ice-action to the same depth ; the effect 

 of glaciers being to deposit moraines between them- 

 selves and the sides of the valley they fill; as also to 

 push forward similar accumulations. Glaciers from each 

 valley, meeting at the fork, where their depth would be 

 700 feet of ice, would both deposit the necessary accumu- 

 lation along the flanks of the great valley, and also throw 

 a barrier across it. The melting waters of such glaciers 

 would accumulate in lakes, confined by the frozen earth, 

 between the moraines and mountains. Such lakes, though 

 on a small scale, are found at the terminations and sides of 

 existing glaciers, and are surrounded by terraces of shingle 

 and debris ; these terraces being laid bare by the sudden 

 drainage of the lakes during seasons of unusual warmth. 

 To explain the phenomena of the Yangma valley, it may be 

 necessary to demand larger lakes and deeper accumulations 

 of debris than are now familiar to us, but the proofs of 

 glaciers having once descended to from 8,000 to 10,000 

 feet in every Sikkim and east Nepal valley communicating 

 with mountains above 16,000 feet elevation, are over- 

 whelming, and the glaciers must, in some cases, have been 



