X TABLE OF COXTENTS. 



assuming a clironological order in minerals, 448 ; in replying to Daka, Hunt 

 asserts that he did not say that the White Jlountain rocks were newer than 

 those of the Green Mountains, 449 ; it is shown, however, that he had said this, 

 450, 451 ; a comimrison of Hunt's statements of what he said with what he 

 really did say, 452 ; Hunt's methods set forth, 453 ; Dana's comments on 

 some of Hunt's statements, 453, 454, 455. Dana remarks that Hunt's volume 

 " contains a series of misrepresentations of the views of others wholly unnecessary 

 and difficult to find excuse for," 454 ; Dana's examination of the Helderberg 

 rocks in the Connecticut Valley, with reference to the question whether the age 

 of strata can be determined by means of the minerals they contain, 454, 455 ; 

 " lithological evidence worse than worthless," 455. Selavyn's opinion of the 

 revolution in Hunt's views, 455 ; metamorphism and mineralization no test of 

 geological age, 455. Lesley, in 1875, states that in Pennsylvania the Huronian 

 or Green Mountain system overlies the Wiiite Mountain series, both being older 

 than the Potsdam, 455 ; Dana's criticism of Lesley's statements, 456 ; Lesley, 

 in 1878, withdraws this opinion, and now considers that the Green Mountains 

 are Palaeozoic and the White Mountains Devonian, 456. Dana (1877, 1879) 

 gives the results of his own and Wing's investigations in Vermont and Western 

 Massachusetts, 456, 457 ; according to these, the limestones of that region are 

 wholly Lower Silurian, and the Taconic slates overlie them, and are of the age 

 of the Hudson River group, 457. Hunt, in 1878, further develops his views 

 in regard to the Upper and Lower Taconic series, 457, 458. Hunt, in 1879, 

 gives the reasons why he formerly referred the Green ilountain rocks to the 

 Quebec group, when he in fact regarded them as Huronian, 458; "official 

 reasons " not only prevented his dissenting from Logan's views, but caused him 

 to affirm their correctness in the strongest possible manner, 458 ; further light 

 on Hunt's methods, 458. Various contradictory statements of C. H. Hitch- 

 cock in regard to Vermont geology, 460, 461 ; in 1877 he considers the Green 

 and the White Mountains " nearer the Laurentian than the Huronian," and in 

 1875 thinks that Emmons understood the relations of the rocks called by him 

 Taconic "better than most of his contemporaries," 460, 461 ; in 1880 he finds 

 that he had been in accord with Dana and Wing for years in their "disbelief in 

 'Taconism,'" 460. Li 1880 and 1881, Dana brings together the evidence in 

 regard to the geological age of the Green Mountain limestones and associated 

 rocks, showing beyond possibility of doubt that they are Lower Silurian, 

 461, 462. 



NEW YOEK. 



Geology of the Adirondacks, 462, 463 ; Hall and Logan's views in 1864, 463. 

 Discovery of Eozoon in Westchester County, 463. Hall on the relations of the 

 limestones of Northern New York, 463, 464. Leeds, in 1877, on the lithology 

 of the Adirondacks, 464 ; his views criticised, 464. BiUTTON on the geology of 

 Kichmond County, 464 ; insufficiency of his data, 465. 



NEW JERSEY. 



H. D. Rogers's views of the age of the gneiss and limestone of this State, 465. 

 Cook on the Azoic rocks, 465, 466 ; some suggestions in regard to points 

 needing further examination, 466 ; origin of the iron ores, 466. 



