105 



since established, and still the work of the Brahmaputra, in the delta, *** is altogether in 

 arrears as compared with that of the Ganges. *** The difficulty for which I would seek an 

 explanation is expressed by the question, why is it, remembering the silt power of the 

 Brahmaputra, that at present the elevation of the river at Gauhnti with 350 miles to run, is 

 apparently lower than the Ganges at Rajmahal within 250 miles of the ocean ? Mr. Ferguson 

 correctly described Assam as in a semi-habitable state. From the Bramahkoond to Dhubri 

 it is under the dominion of the waters. It is in the condition of a delta without the power 

 of vertical growth which a delta must possess. *** As evidence of how these quasi-deltaic 

 conditions obtain, how completely this stationary point of formation has been attained, I may 

 notice a remarkable feature of the Dehing. This large stream drains the southeast terminal 

 corner of the valley, as the Brahmaputra proper does that of the northeast. After leaving 

 the gorge of the h:lls, it flows for several miles over a zone of bhabur, the flat slope formed 

 by the coarser torrented debris. On about the middle of this slope, the river being still at 

 strong torrent, it divides into two approximately equal streams : one flows tolerably direct 

 to the Brahmaputra above Sadya, the other flows along the base of the southern hills, through 

 the rocky gorge of the Tippum range at Jaipur and joins the Brahmaputra more than a 

 hundred miles below Sadya. That a river should form itself into two is necessary proof 

 that it is constructing, not destroying, and that for many years such a bifurcation is 

 maintained, shows that there can be no chose of levels between the two courses." 



I have quoted this passage in extenso from the Memoirs 

 of the Geological Surve of India for 1865, where it forms the last 

 paper of any importance on the Geology of the Assam valley 

 alluvial deposits to date, because it shows how little is known of the 

 origin and progress of these deposits. Of their present state as to in- 

 crease or decrease, of the conditions which have made the general level 

 of the country relative to the river higher between Gauhati and Silghat 

 than it is in the Subansiri and Dehing valleys, of the cause of the 

 production of the curious ridges running from the hills towards the 

 river in the Jorhat and Golaghat districts, or of the isolated plateaux 

 surrounded by low land in Tezpur, Bishnauth and Sibsagar, we know 

 little or nothing. One can but wish that in the near future, for the 

 sake of general knowledge, if not for the sake of the tea, these 

 problems may be tackled by a trained geologist. 



TVPES OF SOIL. 



The soil however of the valley, more or less capable of grow- 

 ing tea, may perhaps, except in the Dibrugarh district, which 

 seems to present the most complicated portion of the valley, be divided 

 into five classes of very different value for purposes of this culture. 

 These may be said to consist of (i) a bed of alluvial micaceous sand 

 skirting the base of the Himalayas in Kamrup, Mangaldai, and, 

 I think, Tezpur and part of Bishnauth ; (2) the soil of the plateaux 

 rising suddenly out of the lower plains in Tezpur (' Tezpur bank") 

 Bishnauth, and probably Sibsagar : (3) a heavy soil composed chiefly 



