Calcutta Delta. 557 



thought, with the dispersed fossils of the valley of the Nerbudda, of the 

 Jumna, and of the Irawaddi. The distance at which the conglome- 

 rate lies from those diluvial strata of which it contains portions, to- 

 gether with the size and weight of the primary fragments of which 

 it is chiefly composed, lead at once to the conclusion, that it must have 

 been deposited by waters possessing far greater power of transport 

 than any of the rivers of the present day, even when most swollen by 

 the periodical rains. 



To overcome this difficulty it has been suggested, that some moun- 

 tains existed within 30 miles of Calcutta, and that streams flowed down 

 from them, bearing along fragments of the rocks which composed those 

 mountains. This doctrine is at once seen to be erroneous, and is refuted 

 by the fact, that the conglomerate from containing fragments of 

 diluvial strata, cannot possibly date beyond the historical era, and 

 therefore, if its component materials were furnished by mountains with- 

 in 30 miles of Calcutta, those mountains ought to be still in existence, 

 because no convulsions equal to their removal have occurred since 

 the present order of things commenced. We must therefore have 

 recourse to other and more powerful agents than our present rivers, 

 and in order to shew what that agent probably was, we must first take 

 a glance at the geological formations which give support to, and from 

 which have been derived the materials of, the alluvial plains. 



It has been shewn already in my geological report on the Western 

 Himalayas, that the great central chain is composed of primary rocks 

 of the usual character; namely, granites, gneiss, mica, and chlorite 

 slates, hornblende and clay slates, while upon either flank of the great 

 belt, rests a series of secondary strata, inclined at a considerable angle 

 with the, horizon. 



These strata of course are at once seen to owe that inclination to the 

 uprise of the central primary chain upon which they lie, and which up- 

 rise or outburst must have taken place subsequent to the deposition of 

 those strata which it afterwards elevated. 



Again, on the outermost southern flank occurs a belt of diluvial depo- 

 sits, containing the remains of vast animals which became extinct at the 

 period of the deluge ; these strata are likewise inclined, and resting in 

 some places upon the secondaries above mentioned. It consequently 

 follows, therefore, in accordance with strict geological reasoning, that 

 their inclination must have taken place subsequent to their deposition, 

 and that it has been occasioned by the uprise of the primary rocks, 

 through the double series of secondary and tertiary formations, which 

 had both been horizontally deposited above them. As a natural con- 



