28 BLANFORD : GEOLOGY OF NAGPtJR. 



character with such remarkable precision. The description of them in 

 Nagpur is the description of them in Bengal, in Orissa, and in the 

 Narbada valley. In every case the grey "mudstones/' the fine pale 

 brown or greenish sandstones with their peculiar tesselated weathering, 

 and the presence of huge transported blocks, generally rounded, are 

 characteristic of the group. 



I doubt if we can yet clearly understand the origin of the ' boulder 



bed.' I suggested in 1856 that the boulders had 

 Origin of boulder bed. 



been transported by ground ice, sunply because 



that was the only way in which I could conceive the occurrence 



of huge rounded boulders in such very fine silt as forms the principal 



portion of the bed. The hypothesis is, I grant, improbable, and 



I should be delighted to abandon it if a better one can be suggested. 



But I cannot subscribe to my colleague Mr. Hughes's comparison 



of the boulder bed to the accumulations formed on the coasts of 



Penang.* In the first place there is no evidence whatever that 



the Talchirs are a mai-ine formation. Not a single marine fossil 



has been found throughout the great plant-bearing series from the 



Tdlehii-s to the Rajmahals, and I cannot help thinking it most probable 



that all were river deposits ; the Talchirs might be lacustrine ; but that 



their being supposed to be so would involve the hypothesis of so 



enormous a lake or series of lakes with similar deposits throughout. 



Still reading lake, for sea, the difficulty appears to me just as great as 



ever. My friend, Mr. Hughes, suggests that the Talchir boulders may 



be weathered round, not rolled. This possibly might account for 



their rounding in some eases, but certainly not in aU. At Korhadi 



the boulders are not only rounded, but they have been brought from 



* Mem. Geol. Suit., India, toI, v, p. 236. It is only proper to add that Mr. Hnghes, 

 ■when making this comparison, had only seen Talchir rocks in places where they appeared to 

 have been truly littoral deposits. He abandoned the idea, when subsequently he found 

 Talchir boulder beds where they could not have been littoral deposits. 

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