CHAP. xvi. GANaETIC MUD AND EUKOPEAN LOESS. 337 



in river cliffs eighty feet high, in which they were unable to 

 detect organic remains, a remark which I found to hold 

 equally in regard to the recent mud of the Mississippi. 



Dr. Wallich, while confirming these observations, informs me 

 that at certain points in Bengal, farther inland, he met with 

 land-shells in the banks of the great river. Borings have 

 been made at Calcutta, beginning not many feet above the 

 sea-level to the depth of 300 and 400 feet ; and wherever or 

 ganic remains were found in the strata pierced through, they 

 were of a fluviatile or terrestrial character, implying, that 

 during a long and gradual subsidence of the country, the 

 sediment thrown down by the Granges and Burrampooter 

 had accumulated at a sufficient rate to prevent the sea from 

 invading that region. 



At the bottom of the borings, after passing through much 

 fine loam, beds of pebbles, sand, and boulders were reached, 

 such as might belong to an ancient river channel ; and the 

 bones of a crocodile, and the shell of a freshwater tortoise 

 imbedded in it, were met with, at the depth of four hundred 

 feet from the surface. No pebbles are now brought down 

 within a great distance of this point, so that the country 

 must once have had a totally different character, and may 

 have had its valleys, hills, and rivers, before all was reduced 

 to one common level by the accumulation upon it of fine 

 Himalayan mud. If the latter were removed during a 

 gradual re-elevation of the country, many old hydrographical 

 basins might reappear, and portions of the loam might alone 

 remain in terraces, on the flanks of hills, or on platforms, at 

 testing the vast extent, in ancient times, of the muddy enve 

 lope. A similar succession of events has, in all likelihood, 

 occurred in Europe during the deposition and denudation of 

 the loess of the post-pliocene period, which, as we have seen 

 in a former chapter, was long enough to allow of the gradual 

 development of almost any amount of such physical changes. 



