Anniversary Address. 29 



but may not be more recent than tliose at Ballarat ; but wbicb 

 seems to have derived its pebbles and boulders from Palaeozoic 

 and Metamorphic and ordinary igneous rocks ; laterite itself 

 covering rocks alike of every older epoch. Occurring as this 

 detrital covering does all over India, and having the same 

 relative position to all kinds of rocks, and at all heights up to 

 that of at least 8000 feet above the sea, the idea of diamond 

 belonging to it as its actual source is not sustainable. 



In asubsequent paper (Q.J.G-.S., vol. xvi.) the Eev. S. Hislop, one 

 of the authors, considers the Intertrappean Tertiary bed as lower 

 Eocene, producing good fossiliferous evidence for this opinion ; 

 and shovs^s that the Mahadeva or Bangnapilly sandstone is about 

 the same age, in which Dr. Oldham seems to coincide. {Memoirs 

 of India, \o\. 1, 171.) Hislop's views have not been thoroughly 

 received by other geologists ; and doubts have been expressed as 

 to whether the trap or basaltic formation of India is not all of one 

 age. 



If compared with the Cudgegong Diamond deposits, the older 

 of which, and from which the younger is derived, underlies the 

 trap (basalt), it will be seen there is a difficulty to be reconciled 

 with respect to each ; and if the diamond conglomerate of India 

 be lower Eocene, that difficulty is complicated by assuming that 

 the Cudgegong deposit is Pliocene, 



On reviewing the whole evidence I am inclined to believe that 

 unless they are much younger than the Pliocene, or Pleistocene 

 epochs, in fact of recent origin, they must be considered as 

 drifted from rocks older than the Carboniferous. As they 

 everywhere exist in limited areas, it would also be a fair inference 

 bhat as there is no want of carbon, and similar agencies must 

 operate over enormous regions, the limited range of diamond is 

 a strong argument against its recent production. If the facts 

 advanced by several of the authorities whom I have quoted are 

 received, then diamond must have undergone processes similar 

 to those that have resulted in the formation of gems, of which 

 there is no dispute as to probable age. 



It is remarkable, how silent observers in general in India are as 

 to the multiplicity of such gems and other extraneous minerals 

 in the Indian diamond regions. Tet Mr. Carter names Quartz, 



