870 



THE WONDERS OF GEOLOGY. Lect. VIII. 



gold and platinum to the Russian government. These 

 metals are obtained, by washing, from the alluvial deposits, 

 which also abound in the bones of mammoths and other 

 huge extinct pachyderms (see ante, p. 154). The gold and 

 platinum have evidently been derived from metalliferous 

 veins that existed in the rocks of the Ural mountains, before 

 that chain was elevated above the reach of alluvial action. 



" The auriferous shingle, with its sub-angular fragments, so com- 

 pletely resembles the detritus of lakes, and is so unlike the gravel of 

 sea-shores, that, independently of the absence of any marine remains 

 whatever all along the immediate eastern flank of the Ural Mountains, 

 there can be no hesitation in believing that the gold detritus was 

 accumulated during a terrestrial and lacustrine condition of the surface. 

 Previously to the elevation of the Urals to their present altitude, they 

 constituted a moderately elevated region, which formed the edge of an 

 eastern continent, inhabited by the mammoths and their associates. 

 The extensive areas now covered by auriferous detritus, were probably 

 then occupied by lakes, into which were drifted, in the course of ages, 

 the bones of the large extinct mammalia which inhabited the surround- 

 ing plains and hills, and the detritus of the rocks and strata. The 

 sudden upheaval of the Ural crest, which has evidently taken place 

 in a comparatively recent period, broke away the barriers of the 

 lakes, and elevated some masses of their shingly bottoms and shores 

 into irregular mounds, which subsequently became desiccated, and 

 now constitute the auriferous alluvia."* 



34. Cupreous deposits. — An illustration of a metallic 

 deposit by the effects of chemical action, without the agency 

 of heat, is afforded by a singular formation of copper ore, 

 which occurs in New Brunswick. In a bed of lignite, 

 which is covered by a few feet of alluvial soil, and rests on 

 a conglomerate, the precise nature of which is not stated, 

 there is a nearly horizontal layer of green carbonate of 

 copper, about eight inches in thickness. The ore is dis- 

 seminated through the lignite, in the same manner as me- 

 tallic ores are usually blended with their accompanying 

 vein-stones. This bed bears a close analogy to the modern 

 * See the Geology of Russia, vol. i. pp. 485 — 487. 



