40 Sir II. I. Murchison on the Silurian Bocks in Cornwall. 



clearly been caused by the action of powerful aqueous drift, in the 

 manner I have elsewhere attempted to explain.* 



Your stanniferous gravel bears, indeed, precisely the same rela- 

 tions to your granites and killas, as the auriferous deposits of the 

 Ural to the eruptive and schistose rocks of that chain. Both are 

 mere local, shingle accumulations, derived from veinstones which have 

 been denuded from the surface of adjacent crystalline rocks. With 

 these analogies there is, however, a marked distinction between Si- 

 beria and Cornwall. All richly auriferous chains (Humboldt first 

 remarked the fact) have a meridian direction, as in the Ural, and 

 various N. and S. parallel ridges in Siberia and other parts of the 

 globe. The axis of Cornwall, on the contrary, is transverse to that 

 direction, viz., from ENE. to WSW. ; and though containing copper 

 ore in common with the Russian mountains, it differs from them in 

 not producing gold or platinum ; whilst it is peculiarly distinguished 

 by containing tin, which is unknown in the Ural. Let us hope that 

 the day is fast approaching, when the cause of the production of such 

 striking phenomena as these will receive some explanation at the 

 hands of those physical philosophers, who are advancing a line of 

 research in which your own countryman, Mr R/. W. Fox, has already 

 so distinguished himself. But if gold exist not (in any appreciable 

 quantity at least) in your otherwise richly endowed mineral county, 

 there are, I am happy to say, good grounds for hope, that in their 

 most distant colony Englishmen may find it abundantly. In an ad- 

 dress to the Royal Geographical Society, delivered in May 1845, 

 when commenting upon the valuable labours of Count Strzelecki in 

 deciphering the structure of the great N. and S. chain which ranges 

 along the eastern shores of Australia, I specially insisted upon its 

 striking resemblances to the Ural Mountains, whether in direction, 

 in structure, or in alluvia ; remarking, by the way, that as yet no 

 gold has been found in this alluvium. I now learn, however, that 

 fine specimens of gold have been found on the western flank of the 

 Australian cordillera, particularly at the settlement of Bathurst, 

 where it occurs in fragments composed of the same matrix (viz., 

 quartz rock) as in the Ural. My friend and associate in the Impe- 

 rial Academy of Petersburg, Colonel Helmersen, has recently sug- 

 gested, that a careful search for gold ore in the Australian detritus 

 will, it is highly probable, lead to its detection in abundance; since 

 the Russians had long colonized the Ural Mountains, and had for 

 many years worked mines of magnetic iron and copper in solid rocks, 

 before the neglected shingle, gravel, and sand, on the slopes of their 

 hills and in their valleys, were found to be auriferous. If, then, in 

 the course of your statistical inquiries, you may know of any good 

 Cornish miner about to seek his fortune in Austraha, be pleased to 



* See Russia in Europe and Ural Mountains; and Journal of the Geol. Soc, 

 No. 8. 



