276 KEMP'S ORE DEPOSITS. 



tered, and apparently exhibit no such grand general relations to 

 these geographical and geological phenomena. 1 



2.16.02. In the Mississippi Valley, W. P. Jenney has re- 

 marked the connection of the antimony and silver deposits of Ar- 

 kansas with the Ouachita uplift that traverses that State and In- 

 dian Territory ; also, the location of the Missouri lead and zinc 

 ores along the Ozark uplift; and he has referred the Wisconsin 

 lead and zinc mines, as well as those in the neighboring part of 

 Iowa and Illinois, to an uplift south of the Archaean area of Wis- 

 consin. The limitation of the Lake Superior copper deposits to the 

 Keweenawan system may be mentioned, and such parallelism as 

 prevails among the Lake Superior iron ores. In the East the great 

 belt of Clinton Ores ; the long succession of Siluro-Cambrian limo- 

 nites in the Great Valley ; the black-band ores and clayironstones- 

 of the Carboniferous ; the closely similar geological relations of 

 nontitaniferous, magnetite lenses in the Archaean gneisses; and 

 the general association of titaniferous magnetites with rocks of the 

 gabbro family the country over all are striking illustrations of 

 broad, general geological features that may characterize extended 

 areas. To these may be appended the great series of pyritous 

 beds or veins in the slates and schists of the East, the gold belt of 

 the southeastern States, and the small copper deposits associated 

 with the Triassic traps and sandstones. Aside from these, while 

 there are important mines not included in the list, the others do 

 not exhibit the same widespread uniformities of structure or asso- 

 ciations. Yet, from the list cited, it forcibly appears that similar 

 conditions have brought about related ore bodies over great 

 stretches of country ; and while in the opening schemes of clas- 

 sification points of difference were emphasized, in the closing pages 

 points of resemblance may be with equal right brought to the fore- 

 ground. 



2.16.03. A few general conclusions suggest themselves from 

 the preceding pages. 



(1) The extreme irregularity in the shape of metalliferous de- 



1 G. F. Becker, Amer. Jour. Sci., 3d Series, Vol. XXIII., 1884 p. 209. 

 W. P. Blake, Rep. Cal State Board of Agriculture, 1866. S. F. Emmons, 

 " The Structural Relations of Ore Deposits," M> E., XVI. 804. R. W. Ray- 

 mond, "Geographical Distribution of Mining Districts in the United 

 States," M. E., I. 33. Fortieth Parallel Survey, Vol. III., Chap. I. " Pre- 

 cious Metals," Tenth Census, Vol. XII. 



