60 

 iODw.j '-* [Wincbcll. 



Ill 1850 Professor Hall resumed the discussion of the parallelism of 

 eastern and western formations, and the parallelism of the whole with the 

 standard systems of Europe. ^^ 



In this celebrated discussion, Professor Hall states that " the shales and 

 sandstones of the Catskill mountains, . . . have no representatives 

 at the "West. Succeeding the Black Shale, however, there is a group of 

 shales and sandstones which, from the fossils they contain, are regarded 

 as belonging to the Carboniferous period. "^7 And again, "the green 

 shales and saiidfetones of Ohio and Indiana, which succeed this Black 

 Shale, have been recognized as carboniferous by their fossils, though 

 there is still some doubt whether the lower part may not represent the 

 Chemung group of New York."2s He still insists on the carboniferous 

 aspect of the rocks from the Marcellus to the Catskill, and cites, after de 

 Verneuil, the Goniatites rotatorius and Qoniatites princeps as proving the 

 carboniferous age of the ' ' Rockford bed ' ' which he regards as embraced 

 in the Marcellus shale, ^s 



About the same date, Mr. Murray^" reported new observations on the 

 Black Shales of Canada West, in the region more recently famous for its 

 production of petroleum. These he still regarded as embraced in the 

 Hamilton Group, and probably continuous with those previously exam- 

 ined at Kettle Point. He remarks that the "bituminous springs [of 

 Enniskillen] probably owe their origin " to this formation. 



In 1851, Mr. Christy^' read a paper before the American Association at 

 its Cincinnati meeting, in which he announced that the Rockford Gonia- 

 tite limestone is centrally located in the Black Slate of Indiana, and ac- 

 cording to Verneuil embraces the carboniferous fossils Qoniatites rotator- 

 ius and O. princeps, and Gyclolohus. Mr. Christy specifies several locali- 

 ties at which the limestone and the slate may be seen in juxtaposition, 

 and accounts for Dr. D. D. Owen's error in pronouncing the limestone a 

 portion of the Cliff limestone. Mr. Christy states that the Goniatite 

 limestone has about 28 feet of black shale below it, and about 30 feet of 

 black shale above it. The latter is succeeded by "about 350 to 400 feet of 

 soft shale with an occasional stratum of limestone and some beds of sand- 

 stone, including fossils. "32 



At the same meeting Col. Whittlesey^^ read a paper "On the equiva- 

 lency of the rocks of north-eastern Ohio, and the Portage, Chemung, and 

 Hamilton rocks of New York." Col. Whittlesey's extended and accurate 

 observations in the state, enabled him to furnish valuable sections of the 

 Ohio strata, to which I shall have occasion again to refer. Following 

 Professor Hall in his paj^er published in 1843, he places the Ohio rocks, 

 from the Cliff limestone to the Conglomerate, in the zone of the New 

 York Upper Devonian. 



In 1853 Dr. D. D. Oweu''^ published a geological map of the North-west, 



'" Foster and Whitney's Rep. Min. Land District, L. Sup., vol. 11., cliap. xviii, p. 2S5. 



2' lb. p. 292. 28 lb. p. ,307. 



29 lb. p. 309. 30 Rep, Progress Geol. Sur. Can., 18.50-51, p. 29, 



3' Proc. Amer. Assoc, vol. v., p. 76. ^^ lb. p. 80. 



23 lb. p. 207. 34 (^eol. Rep. Wis. Iowa, and Minn. 



