Anniversary Address. 7 



Cadgegong River, which these gentlemen- have recently explored 

 and described.* ' 



The opinions expressed by them are to the effect, that the 

 Diamond district is limited to the presence of an ancient drift 

 deposit covered generally by basaltic rocks, and that when 

 found in the river bed, or in alluvial soil, the diamonds are 

 - frequently scratched and broken, whilst in the drift alluded to 

 they are found intact. And at the points where they are thus 

 found in the river bed, they are so found in consequence of the 

 tailings of the miners having been washed thereto. 



The river having changed its course, the area referred to is 

 merely an alluvial space at one of those points. 



The general formations of mare ancient date in the vicinity, 

 are considered to be Upper Silurian traversed by greenstone, 

 with overlying carboniferous beds as outliers of more extended 

 strata. Mr. Norman Taylor has suggested, that the Diamonds 

 have been in some way derived from the carbon in the Coal 

 measures. Opinions as to the derivation of Diamond from 

 vegetable matter by a process of distillation, somewhat like that 

 to which coal is due, and even from animal matter capable of 

 supplying carbon, have been long held by certain philosophers. 



Considering the facts glanced at before,t relating to the 

 transmutation of rocks by heat and other agencies, the formation 

 of Diamond in the humid way does not appear to me an 

 extravagant supposition. But, on examining the sand or deposit 

 in which the Cudgegong Diamonds are found, I was struck with 

 the amount of minute gems, such as zircon, topaz, sapphire, 

 corundum, spinel, pleoruste, &c., which compose the finely sifted 

 material in which gold, is also found ; and Mr. Norman Taylor 

 dwells on the circumstance, that the Diamond is not only 

 associated with the gold (as in most other foreign localities), but 

 with those gems which are held to have had an igneous origin, 



* A paper subsequently read before tlie Eoyal Society, will fee found in the 

 present Volume. 



t " On the Transmutation of Eocks in Australasia," by Eev. W. B. 

 Clarke, M.A. ; read before the Philosophical Society of N.S.W., 10th May, 

 1865, (T. P. S. p. 266). 



