398 PHYSICAL GEOGRAPHY OF SIKKIM. Appendix E. 



efficient natural barrier than the greater height of the less snowed 

 central part of the chain beyond them. 



Though, however, our maps draw the axis through the snowy peaks, 

 they also make the rivers to rise beyond the latter, on the northern 

 slopes as it were, and to flow southwards through gaps in the axis. 

 Such a feature is only reconcilable with the hypothesis of the chain 

 being double, as the Cordillera of Peru and Chili is said to be, geo- 

 graphically, and which in a geological sense it no doubt is : but to 

 the Cordillera the Himalaya offers no parallel. The results of 

 Dr. Thomson's study of the north-west Himalaya and Tibet, and 

 my own of the north-east extreme of Sikkim and Tibet, first gave 

 me an insight into the true structure of this chain. Donkia mountain 

 is the culminant point of an immensely elevated mass of mountains, of 

 greater mean height than a similarly extensive area around Kinchin- 

 junga. It comprises Chumulari, and many other mountains much 

 above 20,000 feet, though none equalling Kinchinjunga, Junnoo, and 

 Kubra. The great lakes of Hamchoo and Cholamoo are placed on it, 

 and the rivers rising on it flow in various directions ; the Painom- 

 choo north-west into the Yaru ; the Arun west to Nepal ; the 

 Teesta south-west through Sikkim ; the Machoo south, and the Pachoo 

 south-east, through Bhotan. All these rivers have their sources far 

 beyond the great snowed mountains, the Arun most conspicuously 

 of all, flowing completely at the back or north of Kinchinjunga. 

 Those that flow southwards, break through no chain, nor do they 

 meet any contraction as they pass the snowy parts of the moimtains 

 which bound the valleys in which they flow, but are bound by 

 uniform ranges of lofty moimtains, which become more snowy 

 as they approach the plains of India. These valleys, however, 

 gradually contract as they descend, being less open in Sikkim and 

 Nepal than in Tibet, though there bounded by rugged mountains, 

 which from being so bare of snow and of vegetation, do not give the 

 same impression of height as the isolated sharper peaks which rise 

 out of a dense forest, and on which the snow limit is 4,000 or 5,000 

 feet lower. 



The fact of the bottom of the river valleys being flatter towards the 

 watershed, is connected with that of their fall being less rapid at that 

 part of their course; this is the consequence of the great extent in 



