28 Anniversary Address. 



Over these beds comes the lower trap rock, which is compact 

 beneath and vesicular at the top, with cresting patches of 

 nodular trap. These traps enclose in places a thin sedimentary 

 formation of Tertiary age, which has an uninterrupted range of 

 1050 miles in one direction, and of 660 miles in the other. 

 Its age has relations with the Eocene of Europe. Notwith- 

 standing the order presented in various parts of this large region, 

 the authors consider the various trap rocks as all younger than 

 these beds, the -lower having in fact been the younger. The trap, 

 they hold to have flowed into and over and to have altered the 

 lowest of these tertiary beds, which were deposited in a series of 

 great lakes of no great depth. 



Above the trap another series of beds occurs, the lowest of 

 which is Laterite, a w^ell-known term to those who are conversant 

 with Eastern Asiatic geology. In this, the authors state, occur 

 the diamond mines east of Nagpur. They dispute the assertion 

 that the diamonds belong to the transmuted sandstones below the 

 trap ; and say that at "Weiragad (about 80 miles S.E. of Nagpur) 

 there is no sandstone, but quartzose metamorphic rocks only^ 

 At that place the diamonds occur in a lateritic conglomerate which 

 overlies the sandstone in other places, and in which ferruginous 

 cements occur formed from the detritus and boulders of adjoining 

 formations ; and this they hold to be the diamond conglemerate. 

 It is therefore assumed to be younger than the overlying trap 

 formation. Above comes in a series of deposits, the lowest of 

 which is brown, the middle red, with existing fluviatile shells, land 

 shells, and bones of mammalia (Avhich Professor Owen has since 

 determined to be those of buffalo and antelope) ; tusks of a 

 large animal were also found in the brown clay. The uppermost 

 deposit of all is the Eegur or black cotton soil, in which Kunkur 

 is mixed. Bones of oxen and sheep are found in it. 



Messrs. Hislop and Hunter consider these Black and Bed clay 

 beds to belong to the Bost-fliocene formations ; the Broicn clay to 

 the newer Pliocene. 



Assuming these Nagpur deposits to be correctly placed, 

 diamonds of India are still, according to evidence collected from 

 other authorities and already considered, traced to a conglomerate 

 which may be more recent than our basalts on the Cudgegong, 



