iS38.] 



in Fort William^ 



475 



deposit at the mouth of a primeval river : the excess of mica contain- 

 ed in it would seem to indicate its derivation from a gneiss or schistose 

 source, .such, indeed, as the present Himalayan or Vindyan range 

 might still furnish. It was evidently anterior to the general and ex- 

 tensive alluvial deposits of the yellow kankary clay which entirely 

 cover, or rather form, the Gangetic plain, and which the auger in Fort 

 William had passed through before it attained the depth of hundred 

 feet. Now the fossil bones of the Jamna were also found 

 under the kankar clays of the Doub, 150 feet below the surface, so 

 that in this respect the situation of the two is similar enough. The 

 calcarious infiltration which has consolidated the sand and gravel of 

 the Sewalik and Nerbudda matrix has been wanting here, and per- 

 haps frora its greater distance from the hills alone, the sand here is 

 in a much more comminuted state geologically speaking, however, 

 the whole of the fossils may belong to the same period of ahuvial 

 deposit— or, in other words, to an indefinitely distant epoch of the 

 present system of quiescent operations in land and flood, whose gra- 

 dual action has subsequently accumulated the superjacent beds of 

 clay, abounding in minute fresh-water shells, extending for thousands 

 of square miles — and again over them towards the delta of the Gaugest 

 other more recent and extensive beds of blue clays, coloured widi ve- 

 getable debris and containing imbedded peat and wocd, by which they 

 are identified with the existing soil of the Sundarban forests. The 

 mind is lost in contemplating the immense periods which such a 

 deposit would demand at the hardly visible rate of present accumula- 

 tion: — yet there are other causes of wonder in the several beds of 

 coarse granitic angular gravel and nodular or pea iron ore which 

 have been traversed by the auger before reaching the fluviatile sand 

 beneath. These may indicate the volcanic upheavement and subse- 

 quently gradual decay of granitic and ferruginous hills, pending the 

 progressive deposit of the alluvium, concerning which, however, we 

 can know nothing certain, and need not therefore lose ourselves in 

 conjectures. In like manner it might be advanced that the whole 

 of the clayey strata were deposited in fresh water as the saliferous 

 sand and sandstone of Upper India has been in salt-water — and that 

 the animals whose exuviae are now brought to light at so many points, 

 were the inhabitants of the borders of a prodigious bason. In the up- 

 per beds of blue clay penetrated in digging tanks and canals, bones 

 have occasionally been met with (see the note on those found at 

 Dumdum in vol. ii., page 649), bur unfortunately none have been pre- 

 served. The occurrence of the remains of quadrupeds at one or two 



