EAST NEPAL AND THE SIKKIM HIMALAYA MOUNTAINS, 89 



by the accumulation and detention of fogs over the rank vegeta- 

 tion which prevails from 8 nearly to P ; and by the lofty moun- 

 tains of K, which shield it from the returning dry currents from 

 the north. In proceeding north all the circumstances that tend to 

 the dispersion of the snow increase, whilst the fall diminishes. 

 At P the deposition is enormous, and the snow-line low — 15,000 

 feet ; whilst at T little falls, and the limit of perpetual snow is 

 19,000 and 20,000 feet. Hence the anomaly, that the snow-line 

 ascends in advancing north to tlie coldest Himalayan regions. 

 The position of the greatest peaks and of the greatest mass of 

 perpetual snow being generally assumed as that of the ridge or 

 watershed, travellers, arguing from single mountains alone, on 

 the meridional ridges, have at one time supported, and at another 

 denied, the assertion, that the snow lies longer and deeper on the 

 north than on the south flank of the Himalaya ridge. 



The great accumulation of snow at 15,000 feet, in the parallel 

 of P, exercises a decided influence on the vegetation. The 

 alpine Rhododendrons R. setosum and R. aiithopogon hardly reach 

 14,000 feet, sometimes not 13,000 feet, in the broad valleys and 

 round-headed spurs of the flanks of Kinchinjunga ; whilst the 

 same species ascend to 16,000, and one to 18,000 feet, at T. 

 Beyond the latter point, again, the great aridity of the climate 

 prevents their growth, and in Tibet there are generally none even 

 as low as 12,000 and 14,000 feet. Glaciers, again, descend to 

 13,000 feet in the tortuous gorges which immediately debouche 

 from the snows of Kinchinjunga, but no plants grow on the 

 debris they carry down, nor is there any sward of grass or herbage 

 at their base, the wliole surrounding atmosphere being chilled by 

 enormous accumulations of snow, and the summer sun rarely 

 warming the soil. At T, again, the glaciers do not descend 

 below 16,000 feet, but a gi-een sward of vegetation creeps up to 

 their bases, dwarf Rhododendrons cover the moraines, and herbs 

 grow on the patches of earth they carry down, which are thawed 

 by the more frequent sunshine, and by the radiation of heat from 

 the unsnowed flanks of the valleys down which these icy streams 

 pour. 



Looking eastward or westward on the map of India, the phe- 

 nomenon of the perpetual snow is regulated by the same laws. 

 From the longitude of Upper Assam in 95° E. to that of Kasli- 

 mir in 75° E. the lowest limit of perpetual snow is about 15,000 

 feet, and the mass of Rhododendrons affect the most humid locali- 

 ties near it, at 12,000 to 14,000. Receding from the plains of 

 India and penetrating the mountains, the climate becomes drier, 

 the snow line rises, and vegetation diminishes, whether the elevation 

 of the land increases or decreases, plants reaching 17,000 and 

 18,000 feet, and the snow line 20,000 feet. To mention extreme 

 cases: the snow level of Sikkini in 27° 30' is at 15,000 



