liv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



great intensity, the denudation of the district was probably much 

 assisted, while a very large proportion of the transported matter was 

 finally carried off in the form of fine sediment by the ordinary action 

 of the sea. Without the aid of this repeated tumultuary action, I 

 cannot, in fact, conceive how all traces of marine deposit and coast 

 action could have so entirely disappeared from the valleys of the 

 Wealden, those of the Highlands, or those of many other regions. 



The Drift which has been described in the papers by Mr. Austen, 

 Mr. Prestwich, Sir Roderick Murchison, and Mr. Martin differs 

 greatly from a large part of the general mass of Drift derived from 

 the north and spread over the wide areas of northern Europe and 

 North America. The difference consists chiefly in the absence of 

 large blocks, the generally unworn character of the constituent ma- 

 terials, and the local origin of the masses here spoken of. Certain 

 portions of superficial masses of this kind, though in a geological 

 view of little more importance than the rest, are now become of im- 

 mense importance in an economic point of view, from the circum- 

 stance of their being auriferous. Two papers, by the Rev. W. B. 

 Clarke and Sir R. I. Murchison, were read at one of our recent 

 meetings on the subject of the auriferous Drift of Australia. 



Mr. Clarke commenced his researches on the geology of the district 

 west of Port Jackson in 1841, and soon observed indications, though 

 very faint, of the existence of gold. Continuing his researches up 

 to a recent period, his convictions became stronger, and were made 

 public through the medium of several local journals, that Australia was 

 an auriferous region of considerable promise. In 1847 he became 

 for the first time acquainted, he says, with the views entertained by 

 Sir R. Murchison respecting the true interpretation of the geological 

 system of Australia, and obtained some knowledge of the auriferous 

 deposits of the Ural Mountains, from the abstract of an account, 

 given to the Geological Society of France by M. de Verneuil, of the 

 researches made by Sir R. Murchison and himself in Russia. Mr. 

 Clarke was thus enabled to institute a comparison between the phse- 

 noniena of the Ural and those of Australia, which he published in 

 the Sydney Herald of September 28, 1847. 



In 1845 Sir R. Murchison and his associates published the 'Geo- 

 logy of Russia in Europe,' containing considerable details, as you will 

 recollect, of the gold-bearing detritus of the Ural Mountains, and of 

 its geological relations to the neighbouring rocks. These rocks con- 

 sist in great part of various schistose quartzose masses, with granites, 

 porphyries, and injected igneous rocks, such as generally charac- 

 terize the axes of mountains belonging to the oldest geological periods 

 in other places ; and the auriferous detritus consists of the local de- 

 bris from these mountainous masses. From this debris nearly the 

 whole of the gold obtained from the Ural Mountains is extracted, very 

 few of the veins in the solid rock being found to yield any consider- 

 able quantity" of ore. The recent geological date of the debris was 

 also established, by the fact of the existence of bones of the mam- 

 moth imbedded in its lowest portions. 



The geological characters and relations of this auriferous Drift 



