IMr. CoLEBROoKE Oil the Norlh-easi of Bengal. 137 



Quitting- the Brahm-putra and its vicinage, research has been extended 

 westward along- the northern frontier of Bengal. The steep banks of rivers 

 present the best and almost the only opportunities of examining the strata : 

 and from two such positions^ where good sections are exhibited^ specimens 

 have been received. 



The Tista, a river which descends from the Bhotan Mountains and traverses 

 North Bengal, is remarkable for a recent, sudden, and great alteration of its 

 course and channel ; analogous to changes which may be inferred from ac- 

 tual appearances to have taken place at remote periods in other instances, in 

 the same and other rivers. The Tista was visited by Mr. Scott at the place 

 where it issues from the lower range of Bhotan hills. He has furnished a 

 sketch of the cliffs, showing the relative positions of the spots whence spe- 

 cimens of the rocks were taken. They consist of sandstone containing much 

 mica, with coal and shale. 



The Subukj another river issuing from the Bhotan Mountains, was also visited 

 by Mr. Scott, at the place where it quits the lower hills ; and he has furnished 

 a similar sketch of the appearance of the hills as cut by the river. The rock is 

 here quite similar to that which was found composing the banks of the Tista ; 

 and likewise consists of sandstone containing mica, with coal and slate clay. 



These hills may be considered to be fair samples of the entire range which 

 skirts the north of Hindustan. They rise to no great elevation, and constitute 

 the first step from the plain of India, ascending towards the mountains of 

 Bhotan and the loftier peaks of the Himalaya. Every where, so far as is yet 

 ascertained, the lower range of hills consists of sandstone, and nearly of the 

 same characterj abounding in mica. 



APPENDIX. 



The following are the sketches communicated by D. Scott, Esq. and re- 

 ferred to by Mr. Colebrooke at the close of the preceding paper : they were 

 accompanied by the specimens described below, collected from the banks of 

 the Tista and Subuk rivers, where they issue from the Bhotan Mountains. — 

 The sketches, Mr. Scott remarks, have no pretensions to accuracy, and are 

 merely intended to show the general appearance of the ranges of hills, and 

 to point out the relative positions of the specimens which are indicated by the 

 figures. 



VOL. VI. T 



