192 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Metallic Products. 



The protrusions of igneous rocks along the line of the Urals were 

 accompanied throughout a great part of the chain by the formation 

 of numerous and extensive metallic veins, particularly on the eastern 

 flanks, the chief seat of the metallic riches of Russia, especially in 

 copper and iron. The geological details connected with these me- 

 talliferous rocks constitute a large and interesting part of Sir R. 

 Murchison's work. One of the most important geological features 

 connected with them, and it is one which appears to be well esta- 

 blished, is the comparatively recent date of the eruptions which 

 brought these metallic products of nature's crucibles within the 

 reach of man. The accounts of the rich gold deposits are curious, 

 and the ejection of the rock in which that metal is contained ap- 

 pears to have been very modern — little, if at all, anterior to the 

 destruction of the mammoths, whose remains are entombed in the 

 gravel which is found everywhere in the depressions of the Ural 

 chain, and which covers vast regions of Siberia. The matrix ap- 

 pears to be quartz in the form of veins, but to find the gold in 

 that state is extremely rare. It is found in lumps and grains that 

 have been rolled, mixed with other detrital matter. A lump weigh- 

 ing about seventy-eight pounds English, found in 1843, is now in 

 the Museum of the Imperial School of Mines at St. Petersburg. 



Several curious facts are adduced to show that some of the ores 

 of copper, particularly the green carbonate or malachite, are 

 aqueous productions, derived from pre-existing ores, as calcareous 

 stalagmites are derived from limestone rocks. In the copper mine 

 of Nijny Tagilsk, at a depth of 280 feet from the surface, an im- 

 mense irregularly-shaped botryoidal mass of solid pure malachite 

 was found, of a bulk estimated at upwards of half a million of pounds 

 weight, presenting in its interior the wavy radiations and silky struc- 

 ture of that beautiful mineral; almost identical in structure with 

 many calcareous semi- crystalline minerals, of whose aqueous origin 

 no doubt exists. 



All the best iron of Russia is brought from the Ural chain and 

 its flanks. It is found in veins in greenstones, and intermixed with 

 the mass of erupted rocks of that class, often in great abundance at 

 the junction of the igneous and stratified rocks, these last being in 

 a metamorphic state. Magnetic iron ore is the chief form in which 

 the metal is found, and it constitutes vast masses, sometimes worked 

 in an open quarry. 



Changes in the Relative Level of Sea and Land, 



You are well aware that proofs of changes in the relative level of 

 the sea and land along certain shores, particularly in the Baltic and 

 Mediterranean, since our continents and adjacent islands were 

 bounded by their present lines of coast, had attracted the atten- 

 tion of some of the earlier geologists ; but it is only within a com- 

 paratively recent period that the discovery, in numerous instances, 

 of the action of the sea at elevations far above its present level, 

 in what have been termed raised beaches^ has excited due attention 



