GEOLOGY. 253 



to be far superior to that at Bristol, which last year paid a net profit 

 of $120,000, and is growing better and richer Qvery foot that it in- 

 creases in depth. Bridgeport Farmer, Jan. 8, 1850. 



DISCOVERY OF METALLIFEROUS DEPOSITS. 



M. BUR AT, in a paper in the Annales des Mines, " On the Continuity 

 of Metalliferous Deposits in Depth," observes : The only promi- 

 nent facts which may be cited as discoveries of the nineteenth century, 

 are, 1st. The washings of the auriferous sands of the Ural, which 

 have increased to an annual produce of more than 10,000 kilograms* 

 of gold ; 2d. The copper mines wrought in the island of Cuba, in 

 the neighbourhood of Santiago, which were opened in 1833, on the old 

 works, and now send 40,000 tons of the mineral to Swansea ; 3d. 

 The calamine mines of Belgium and Rhenish Prussia, which, from a 

 produce scarcely worth naming, now yield 12,000,000 kilograms of 

 zinc; 4th. The lead mines of Missouri and Illinois, the importance 

 of which is not yet appreciated, but which, it is said, would produce 

 30,000,000 kilograms of lead; 5th. The copper mines of Lake 

 Superior, the working of which is projected on a large scale. To 

 these, says Prof. Jameson, we may add the very productive mines of 

 red copper ore, and green and blue malachite, of Bura-Bura, in Aus- 

 tralia. And, also, the gold washings on the Sacramento River, in Alta 

 California. 



DISTRIBUTION OF GOLD ORE OVER THE SURFACE OF THE GLOBE. 



AT the late meeting of the British Association, Sir R. I. Murchi- 

 son drew attention to the distribution of gold over the surface of the 

 globe, and to a comparison between the auriferous deposits of the 

 Ural Mountains and California. As the result of observations among 

 the Ural Mountains, he had formed the opinion that gold veins had 

 generally been produced wherever certain rocks of intrusive charac- 

 ter namely, greenstones, porphyries, sienites, granites, and serpen- 

 tines had been intruded through paleozoic rocks. It was, in short, 

 among clay-slates, limestones, and grauwacke-sandstones which had 

 been penetrated by such igneous rocks, that quartz veins abounded, 

 and with them a diffusion of gold ore in veins, leaf, and grains. To 

 the general view of Baron Humboldt, that the richest gold deposits 

 were those which were derived from ridges having a meridian direc- 

 tion, several geologists were decidedly opposed ; but Sir Roderick was 

 of opinion, that although they might not be able to explain the cause, 

 it was a fact that the greatest quantity of gold ore had been obtained 

 from chains having a nearer relation to north and south than to the 

 equatorial, or east and west directions. This, however, might be due 

 to the general form of the chief masses of land, and to the prevailing 

 strike of the paleozoic rocks. Humboldt, in view of the great lumps 

 occasionally found in the surface rubbish, had supposed that there 



* A kilogram equals 21b. 3oz. Avoirdupois. 



22 



