OF WESTERN AND CENTRAL INDIA. 19 



to observed phenomena, but that it involves a series of physical 

 impossibilities. 



Of course it is highly probable that local instances do occur of 

 small intrusions of trap being inserted among- and beneath the bed of 

 the intertrappeans. I believe I have myself seen one instance. But 

 there is a wide diflference between a merely local intrusion, extending in 

 each instance probably for but a few yards, and very possibly issuing 

 from the overlying bed at the period of its deposition, and the injection 

 of a mass of igneous matter throughout hundreds of square miles of 

 country. 



I am disposed to believe that the beds of the intertrappeans have 

 each but a small lateral extension. I have certainly seen them thin out 

 and disappear within a few miles, and have never succeeded in tracing 

 them to any distance. Mr. Hislop considered that he had traced them 

 continuously from Nagpoor to EUichpoor^. Mr. Wynne and I only 

 found them in a few isolated spots in the intermediate country, and we 

 searched in vain in many places for any indication of their existence. 



To me the occurrence of lacustrine deposits interstratified with trap 

 flows appears so natural a phenomenon that their absence would be 

 more remarkable than their presence. For when first lava flows are 

 poured over the irregular surface of a country shaped by sub -aerial 

 denudation, as the surface of India aj)pears to have been shaped before 

 the first volcanic outbursts, hollows must be filled up and rivers dammed, 

 so that shallow lakes will be formed. These will not, in all probability, 

 be of any large size. Fresh flows of lava will fill up the first lakes, but 

 by damming up other hollows, will produce new ones, and so on, until 

 by the constant accumulation of volcanic material the land has either 

 been reduced to a plane, or the intervals between different lava flows are 



* Quar. Jour. Geol. Soc, Vol. XI, p. 363. 



( 155 ) 



