INTRODUCTORY ESSAY. 169 



estimates usually formed of the steepness of these mountains. 

 The chain does not run due east and west, its western extre- 

 mity being in 35° north latitude, while the latitude of the 

 east end is only 28° north. 



Though the Gangetic and Panjab plains, from which the 

 Himalaya rises abruptly, are for the most part devoid of trees, 

 or covered only with scattered jungle, there is usually a belt 

 of forest ten or twenty miles in width, along the base of the 

 mountains, composed of the same trees which form the mass 

 of the tropical vegetation of the lower hills. 



The extension of the forest over the plain is no doubt 

 the effect of the equable and humid climate which prevails 

 along the base of the mountains, but the nature of the drain- 

 age is also not without its influence. The forest grows usually 

 on slightly inclined gravelly slopes, and is succeeded on the 

 side furthest from the mountains by a swampy tract, without 

 trees, and covered with long grasses, called the Terai. Beyond 

 the Terai the surface generally rises again slightly, so that 

 the swampy tract may be regarded as a series of flat-floored 

 valleys, skirting the base of the mountains; or rather, in a 



strictly scientific point of view, it consists simply of the out- 

 ermost valleys themselves, and the bases of the mountains 

 forming scarcely perceptible undulations between them. 



* 



Immediately within the mountains the first series of late- 

 ral valleys are often broad and bounded by low hills, or on 

 one side (the southern) by low hills, and on the other (the 

 northern) by considerably higher ones. These are known 

 by the name of Dhuns (Doons) ; and when very open, flat- 

 floored, and with gradually sloping beds, their true relation 

 to the surrounding mountain-chains is not at once apparent. 

 Sometimes they appear to be indefinitely extended east and 

 west, in a direction parallel to the Himalayan chain; and, 

 running from one great river to another, they appear to belong 

 to a different order of valleys from what occur further within 

 the mountains. This arises in some cases from the slope 

 of their beds being so extremely gradual, that the watershed 



g 



