1S70.] '*'-'♦-' [Wincliell. 



the Black Schists which represent the Genesee Slate, and to a calcareous 

 band which represents at once the Corniferous and Onondaga limestones 

 and the Hamilton group of the State of New York." 



In his comments upon this paper of de Yerneuil, from Avhich I just 

 quoted, Professor Hall himself says :•■*' ' 'We know that between the Chemung 

 group and the great Carboniferous Limestone of the West and scmthwest, 

 there is an extensive formation of yellow sandstones and green shales and 

 sandstones" — and, for the sake of enforcing a view which he then held, 

 that even the Chemung strata ought to go into the Carboniferous system, 

 he adds, "charged with fossils having a close analogy with those of the 

 groups below." Still further in his tabular arrangement appended to his 

 elaborate discussion on the " Parellelism of the Paleozoic Deposits of the 

 United States and Europe, ''^^ he places the "Yellow sandstones and green 

 shales of Ohio," not only above the Chemung, but above the shales and 

 sandstones of the Catskill mountains." 



In the presence of such facts and such testimony as have been cited, it 

 becomes a question of curious interest upon what grounds the geological 

 equivalency of the Chemung and Marshall can still be maintained. In a 

 paper ptresented before the National Academy last summer (1867) at Hart- 

 ford, and repeated before the American Association at Burlington, it was 

 held that the Devonian fauna of the Chemung in its western extension 

 becomes replaced by the Carboniferous fauna of the Marshall simply 

 through the influence of local conditions. Geographical variations were 

 pointed out in the nature of the deposits and the accompanying faunas, 

 of the Trenton, Hudson River, Niagara and Hamilton groups, and it was 

 maintained that the paleontological contrast between the Chemung and 

 the Marshall is something of the same kind, and possessing no different 

 significance. These views at Hartford, were endorsed by the high autho- 

 rity of Professor Agassiz. 



The same views had been previously recorded by Professor Hall in the 

 Fourth Volume of the Paleontology of New York, ''"' as follows : "We 

 have every reason to believe that, in those sedimentary formations be- 

 tween the Hamilton group and the Coal measures in the east, and between 

 the same group and the Burlington (Carboniferous) limestone in the west, 

 the Devonian aspect of the fauna, on the one hand, and the Carboniferous 

 aspect on the other, are due, in a great degree, to geographical and phys- 

 ical conditions, and not to difference of age or chronological sequence of 

 the beds containing the fossils." 



Again, in a pamphlet " Notice" '*'' of this volume, in alluding to the 

 contrast between the faunas of the Chemung and Marshall groups, he 

 uses these remarkable words:— "TAe distinction between Devonian and 

 Carboniferous faunas is based as often u'pon geographical as chronological 

 relations." 



"I Amer. Jour. Sci. [2] v. 368, >fote. 



'■•2 Foster and Whitney Rep. L. Sup. Land Dis. II, Chap- xviii. 



i« pp. 2.52-2.57. See Notice of tliis volume, Trans. Amer. Pliil. Soc, May, 1S66, p. 2-1 G ; also, 

 Pamplilet, 1867. 



"« Notice of IVtli volume Pal. N. Y.,1S07, p. 5. 



