456 Remarks on the Dejmsits 



Lieut. Smith remarks that from the lower surface of the 

 black peat clay, which rests on the lower conglomerate at 

 a depth of 390 feet, fragments of coal were found, and beneath 

 these, at some distance in the midst of the conglomerate 

 or gravel, bones of a kind of lizard or crocodile were found, 

 and still lower down, at a depth of 464^ feet, fragments of 

 lignite. 



These remains, as well as the nature of the gravel in 

 which they are found, unquestionably indicate the close 

 vicinity of bold rocky mountains at no greater distance than 

 20 or 30 miles, and from which similar torrents descended 

 to those which now fall into the valley of Assam. 



Reposing on the coarse conglomerate, above alluded to, 

 there is a series of layers, twelve feet deep, consisting of cal- 

 careous clay and decayed wood, which from their nature 

 could not have been deposited at any depth beneath water. 

 We must conclude, in fact, that these beds were formed on 

 dry land, which afterwards by series of movements indicated 

 by the beds of gravel, sunk down bodily to their present depth 

 of 390 feet below the level of the sea, as it is quite impossi- 

 ble to understand how drift wood could be separately depo- 

 sited at such a depth. The lower conglomerate therefore 

 affords all the proofs of having been derived from mountain 

 rocks of sufficient altitude, within 30 miles of Calcutta, 

 to render the river currents as rapid as the falls of upper 

 Assam, and this would seem to have continued during a 

 period required to deposit a depth of at least 60 feet of gra- 

 vel, when the transporting power of the currents became 

 suddenly arrested ; for we have reposing on the gravel a 

 bed of drift wood and lacustrine clay containing fragments 

 of a very soft friable shell, of which we find no example in 

 superincumbent beds, or in the recent deposits now forming at 

 the head of the Bay.* This last change clearly indicates a 



* We are indebted to Capt. Lloyd Marine Surveyor General, for a 

 series of deposits from the head of the Bay, taken at various depths from 

 2, to 200 fathoms. 



