of the Calcutta basin. 453 



ject, as if he had been engaged in the tedious and difficult 

 operation itself, during the five or six years which this work 

 has been in progress. 



The sections of deltas can only become known by works 

 of this nature, which from the expense and difficulty attend- 

 ing them, must always be extremely rare. When they are 

 undertaken and carried on with so much spirit as in the 

 present case, it is due to the liberality of the Government, as 

 well as to those intrusted with their management, to make 

 the scientific world acquainted with the result, and this duty 

 could not have fallen into better hands than those of Lieut. 

 Smith, who has left nothing undone but what others may 

 accomplish from the details he has laid before them. The 

 first question that occurs after the perusal of Mr. Smith's 

 paper is, whether the deposits beneath Calcutta have been 

 formed from Gangetic sediments similar to those now forming 

 at the head of the Bay ? So great is the quantity of mud 

 and sand poured out by the Ganges into the Gulph at flood 

 season, says Mr. Lyell on the authority of Major Rennell, 

 that the sea only recovers its transparence at a distance of 

 sixty miles from the coast. The general slope therefore of 

 the strata must be extremely gradual. By charts recently 

 published, it appears that there is a gradual deepening from 

 four to about sixty fathoms, as we proceed from the base 

 of the delta to the distance of about 100 miles into the Bay 

 of Bengal. If we suppose the deposits beneath Calcutta to 

 have the same inclination as those now forming at the head 

 of the Bay, and to have been formed by the same tranquil 

 causes that are now producing new lands from the deposits 

 of the Ganges, the sea face of the delta would necessarily 

 have been situated 125 miles north of Calcutta, or half way 

 between Morshedabad and Malda, at a time when the coarse 

 conglomerate 580 feet below Fort William was deposited. 

 Mr. Lyell, from data furnished by Mr. Everest, calculated 

 the annual deposit of mud discharged at the mouths of the 



