TOPOGRAPHY. 27 



There are two important points to be noted in connection 

 with the Bhabar deposits, which have a controlling influence on 

 the distribution of the Bhabar sal forests : 



(1) The xarge rivers (i.e., the Ganges, Eamganga, Kosi, Sarda 

 and possibly all the big Nepal rivers) have scarcely any Bhabar 

 deposits ivhere they leave the liills. while the small rivers and large 

 streams (e.g., the Nihal, Kalaunia, Gaula and Nandhaur rivers) 

 have enotmous Bhabar deposits. At the same time these larger 

 rivers are in evert/ case characterised by extensive boulder deposits 

 appearing in the foot hills in their vicinity (the Upper Siwalik 

 conglomerate) and in the Duns which adjoin their courses before 

 they finally leave the hills, e.g.. Dehra Dun, Patli Dun, Kotah 

 Dun and the Khaldunga Dun, while all the smaller rivers 

 have no such duns or conglomerate deposits. The evidence as 

 Middlemiss 8 has pointed out is conclusive that the real Bhabar 

 deposits of the large rivers have been caught up in the last earth 

 movements of the Himalayan building, and what Troup calls the 

 Dun type is the same as the Bhabar type. 



(2) The forest vegetation of the Bhabar is exceedingly variable, 

 In the broad gravelly river beds are found thickets and stretches 

 of sissoo (Dalbergia t>isi>ou) and khair (Acacia catechu) ;. on the 

 next level are found forests of Holoptelia infcgrifolia ; on the 

 higher level riverain plateaux occur miscellaneous forests, with 

 large number of mixed species of growing economic importance,, 

 while on the highest plateaux are found sal forests in their beat 

 and finest development. 



4. The Tarai. Where the Bhabar gravels stop the Tarai 

 begins. A belt of country characterised by numerous springs and 

 swamps, by its malarial and unhealthy climate, and by numerous 

 stretches of heavy elephant grasses interspersed with bands of sal 

 and miscellaneous forests, in which simal (Bombax malabaricum) 

 is an important species. The soil is deep fertile loam, the beginning 

 of the characteristic loam of the Gangetic plain. The Tarai 



H Memoirs of the Geological Survey. 



