20 T15APS AXU INTKHTItAfPEAN BEDS 



loo short to allow of the accumulation of sedimentary deposits. It is 

 even possibb that the region may have become barren and desolate, 

 unfitted for organic existence, or that, from changes in the meteorological 

 conditions caused by the volcanic phenomena and the destruction of 

 vegetation, rain might cease to fall in the country. These last are mere 

 conjectures, perhaps improbable, and scarcely warranted by the conditions 

 of any known existing volcanic region, but no existing volcanic region 

 approaches in magnitude to that of the Deccan. It is in any case 

 easy to understand that when rest from volcanic disturbances, showers 

 of ash, and lava flows, permitted sedimentary deposits again to 

 accumulate in the intervals between eruptions, the old lacustrine fauna 

 of the district had died out, and the change had taken place, which 

 is indicated by the fossils of the Bombay intertrappeans. It is also 

 in accordance with probability, I think, to suppose that the volcanic 

 energy was less^ the flows more partial, and the periods of intermission 

 longer, at the commencement and towards the close of the trap epoch, 

 than in the middle of the period. 



The above theory, I think, accounts naturally and easily for all the 

 phenomena of the Central Indian and Bombay intertrappean beds. It 

 explains why tlie sedimentary beds sometimes occur at the base of all 

 the traps ; it accounts for several successive deposits, for their limited 

 and irregular distribution, and also, though I confess less completely, 

 for their absence in the great mass of the trap formation. 



13. Geological age of Deccan and Malwa traps. — There is yet 

 one more question to be treated, and that is the geological age of the 

 traps. The latest and most important contribution to this subject is 

 again Mr. Hislop's paper, so often quoted. He concludes that the traps 

 are of lower eocene age. The same opinion has been held by others, and 

 I entirely coincided in it myself until very lately. Mr. Hislop^s argu- 

 ments are, — the great similarity between the freshwater shells of the 



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