252 CLIMATE OF HIMALAYA. 



The forest belt which skirts the base of the mountains rests 

 for the most part upon a dry gravelly soil, which slopes some- 

 what rapidly, though not perceptibly to the eye, toward the 

 open plains, and is generally dry. Just outside the forest, or 

 sometimes still interspersed with patches of wooded ground, 

 there is generally a low swampy tract, which is lower than the 

 country immediately beyond, and from wliich the water drains 

 away slowly and with difficulty. This is the Terai par excellence, 

 and is, from the constant dampness of the soil, and the dense 

 beat of the summer, peculiarly unhealthy. It is too low and too 

 unhealthy to be much cultivated, and is generally covered by a 

 dense jungle of tall grasses, species principally of Saccharum, 

 Arundo, Andropogon, and Anthisfiria, which rise high enough 

 to cover an elephant, and afford shelter during the greater part 

 of the year for multitudes of tigers and other wild animals. At 

 the commencement of the cold weather, this long grass is set on 

 fii'e and burnt down by the inhabitants of the hills, who at that 

 season descend to the level country to feed their cattle and flocks. 

 It is again abandoned to itself at the commencement of the hot 

 season, as soon as grassy vegetation has made sufficient progress 

 in the mountains. These swampy tracts are a series of lateral 

 valleys which run parallel to the base of the mountains, and 

 which, from being very slightly inclined, present great obstacles 

 to the escape of the w'ater discharged into them by numerous 

 streams from the mountains. 



Along many parts of the Himalaya, a similar series of valleys, 

 nearly parallel to the axis of the chain, but bounded externally 

 by hills of from 2000 to 4000 feet in elevation, may be observed. 

 These valleys are known in the western Himalaya by the name 

 of Dhuns. One of the largest of them is the Deyra Dhun, well 

 known to Indi:in travellers as being traversed en route to Masuri ; 

 a favourite hill station, and now celebrated as the seat of an 

 extensive cultivation of tea in a climate which seems to suit 

 admirably that valuable plant. The Deyra Dhiin is in its 

 centre or highest part, from which it slopes down both to east 

 and west towards the Ganges and Jumna, about 2500 feet above 

 the level of the sea, or 1500 feet above the level of the plains, 

 immediately outside of its bounding range. 



Other Dhuns occur all along the hills to the westward. They are 

 bounded on the north by the ancient rocks of the Himalaya, but on 

 their outer side always by the tertiary sandstones and conglome- 

 rates, now so well known from the.labours of Falconer and Cautley, 

 as the Sewalik formation. In the nortli of the Punjab there are 

 often several series of these valleys, the iimermost only resting on 

 transition rocks, the others excavated out of the tertiary sand- 

 stones, which have there often a width of from 30 to 50 miles. 



