290 MINES 



older deposits. It should be added, however, that although the chlorides of Treasury 

 Hill are as pure as those of Lander Hill, they do not appear, like the latter, to yield 

 in depth to such silver ores as characterize the fissure-veins of Eeese-river district 

 ruby-silver, for instance. Nor are they fissure-veins, so far as we can now decide. 



To the tertiary period of orographical disturbance are referred the volcanic over- 

 flows and the veins wholly or partly inclosed in volcanic rocks. Under this head 

 Mr. King classes many important veins of Mexico, several of those which border the 

 Colorado river in the United States, and, in general, that zone which lies along the 

 eastern base of the Sierra Nevada. The Comstock lode is adduced as the most pro- 

 minent example of this type, and the Owyhee district in Idaho is also referred to it, 

 because, although in granite, it presents a series of volcanic dykes, which appear to 

 prove, by the manner of their intersections with the quartz lodes, that the latter are 

 of tertiary origin. It will be seen that although the extent and number of the de- 

 posits of this class are inferior to those of the earlier period, they include some of the 

 most brilliant instances in the history of mining. As Mr. King, however, points 

 out, many of the veins "which are wholly inclosed in the older rocks may never- 

 theless be due to this later period of disturbance. Nor does he ignore the bearing 

 of this thought on his determination of the early period as Jurassic. He confesses 

 that in more recent strata, formed from debris of Jurassic rocks, ore-bearing pebbles 

 have not been found ; but he regards this fact as a piece of negative evidence merely. 



The distribution of mineral deposits east of the Rocky mountains follows somewhat 

 different laws. Here we have but one longitudinal range, that of the AUeghanies, 

 which is accompanied by a gold-bearing zone of irregular extent and value. In the 

 Southern States the strata flanking this range present a remarkable variety of mineral 

 deposits. On the eastern slope of the Rocky mountains, again, occurs -what may 

 perhaps be denominated a zone or longitudinal series of coal-fields. But between 

 these mountain boundaries the geological formations of the country cluster, as it were, 

 around centres or basins. We have such a group in Michigan, another in the Middle 

 States, and a third in the South-west. 



The deposits of the different metals, ores, and useful minerals, in the country east 

 of the Kocky mountains, vary -widely in age. The ores of gold, copper, and iron, in 

 the pre-Silurian schists of the south ; the galena and cobalt ores of the south-west, and 

 the copper ores of Lake Superior, in the lower Silurian rocks ; the argillaceous iron 

 ores of New York, and other States -west of New York, in the upper Silurian, and the 

 salines of the same group ; the bitumen, salt, coal, and iron ores of the Subcarbon- 

 iferous ; the coal and iron of the Carboniferous ; the coal, copper, and barytes of the 

 Triassic ; the lignites of the Cretaceous ; and the fossil phosphates of the Tertiary 

 period ; are instances which may serve to show how great is this variety. It is not 

 within the province of this paper to discuss the mineral deposits of the Mississippi 

 basin, the Appalachian chain, or the Atlantic coast. I shall content myself -with 

 brief mention of two points. The first is the greater relative age of the metalliferous 

 deposits as compared with those of the inland basin and the Pacific slope. On this 

 side the period of greatest activity in such formations was over before it began in the 

 west. The great gold and silver deposits beyond the Rocky mountains appear to be 

 post-Devonian, post-Jurassic, and even Tertiary in their origin. The vast volcanic 

 activity which affected so wide an area in California, Oregon, Washington, Idaho, and 

 Nevada, is not represented in the east. 



The other point is the peculiar relative position of our coal and iron deposits. 

 This was eloquently described by Mr. Abrams Hewitt, United States Commissioner 

 to the Paris Exposition, in his admirable review of the iron and steel industry of the 

 world. I cannot do better than quote his forcible words : 



' The position of the coal-measures of the United States suggests the idea of a 

 gigantic bowl filled with treasure, the outer rim of which skirts along the Atlantic to 

 the Gulf of Mexico, and thence, returning by the plains which lie at the eastern base 

 of the Rocky mountains, passes by the great lakes to the place of beginning, on the 

 borders of Pennsylvania and New York. The rim of the basin is filled with exhaust- 

 less stores of iron ores of every variety, and of the best quality. In seeking the 

 natural channels of water-communication, whether on the north, east, south, or west, 

 the coal must cut this metalliferous rim ; and, in its turn, the iron ore may be carried 

 back to the coal, to be used in conjunction with the carboniferous ores, which are 

 quite as abundant in the United States as they are in England, but hitherto have 

 been left unwrought, in consequence of the cheaper rate of procuring the richer ores 

 from the rim of the basin. Along the Atlantic slope, in the highland range, from the 

 borders of the Hudson river to the state of Georgia, a distance of 1,000 miles, is 

 found the great magnetic range, traversing seven entire States in its length mid 

 course. Parallel with this, in the great limestone valley which* lies along the margin 

 of the coal-field, are the brown haematites, in such quantities at some points, espe- 

 cially in Virginia, Tennessee, and Alabama, as to fairly stagger the imagination. 





