Xii TABLE OF CONTENTS. 



ARKANSAS. 



Owen's views in regard to the crystalline rocks of this State ; he holds that they are 

 eniptive, 482. 



MISSOURI. 



Nothing d(>finite known in regard to the crystalline rocks of this State, except that 

 most, if not all, of them are eruptive, 482 ; they have been assigned to the 

 Huronian and Laurentian on lithological grounds solely, 482. 



MICHIGAN AND WISCONSIN. 



Reference to work recently published by Wadsworth in regard to the geology of 

 this region, 482. Age of the cupriferous rocks of Lake Superior discussed, 

 482-494 ; evidence obtained on branch of Torch River, 482-485 ; nature of 

 these rocks indicated, 483 ; the facts discussed, 484 ; conclusions reached, 485. 

 Irving, in 1873-74, on the relations of the Lake Superior rocks, 485, 486 ; 

 he adopts a different theory, in part, in 1879, 486 ; Sweet states facts in oppo- 

 sition to the views of Irving, 486 ; our explanation of the phenomena, 487. 

 Irving finds evidence in support of his views at the Dalles, 487 ; Chamberlin 

 holds the same opinion of this locality, 488. Selwyn, in 1882, states his views 

 as to the age and relations of the Lake Superior rocks, which he had previously 

 called Huronian, 488 ; these views identical with those of Foster and Whit- 

 ney, published in 1850, 488. Irving replies to Selwyn, 489 ; Wadsworth 

 replies to Irving, 489. Hunt, in 1883, states that Logan, in 1863, put forth 

 conclusive evidence that the cupriferous rocks of Lake Superior underlaid, un- 

 conformably, the Potsdam sandstone, 489 ; Wadsworth points out that Logan 

 brought no such evidence, 489. N. H. Winchell agrees with Foster and 

 Whitney, and with Selwyn, 480. Chamberlin sums up his reasons for sup- 

 posing the Keweenaw rocks distinct from the adjacent sandstones, 489, 490 ; the 

 errors in his reasoning pointed out, 490. Eesurni of the facts at the Taylor's 

 Falls locality, 490 ; assumptions of the Wisconsin geologists, 490 ; what Owen 

 saw there in 1850, 490, 491. Observations of Kloos, in Report for 1881, 491. 

 . N. H. Winchell thinks the sandstone at this locality more recent than the 

 Potsdam, 491. Errors fallen into by Irving and Chamberlin pointed out, 

 491. The so-called " Keweenawan Series " owes its origin to incorrect observa- 

 tions, and erroneous deductions, 491, 492 ; N. H. Winchell, in 1881, gives a 

 summary of the opinions held regarding the coitper-bearing rocks, made up from 

 one previously published by Wadsworth, 492. Wadsworth points out the 

 ignorance of the principles of geology and lithology displayed by Brooks and 

 Pumpelly, 492 ; they borrow largely from Foster and Whitney's map without 

 giving any credit, 492. Rominger on the Azoic rocks of Michigan, 492, 493 ; 

 his views in regard to the eruptive character of the granites, 493 ; his peculiar 

 theories of the erujrtive rocks, 493, 494 ; his observations in the Menominee 

 region, 494. Discussion of the origin of the iron ores in a previous publication, 

 by Wadsworth, referred to, 494. The views maintained by Foster and Whit- 

 ney, and by Wadsworth, sustained by Selwyn, 494 ; these views opjjosed by 

 Dana, 494 ; his reasoning criticised, 494 ; Newberry also expresses his opinion 



