136 



The French Corals are known to me by a series I possess from 

 the Devonian Limestone of the Bonlonnais, all of which are 

 figured by MM. Edwards and Haime ; the German Corals from 

 the Devonian of the Eifel have been long known to Geologists 

 by the fine figures given of them by M, Hohe, in the Petrefacta 

 Germanice of Goldpuss, to which the student is referred. 



The Devonian rocks attain a great thickness and development 

 in the state of New York, where they are nearly horizontal and 

 undisturbed, so that the natural order of their super-position 

 can be satisfactorily deciphered; they admit of a subdivision into 

 an Upper and Lower series: — 



r CatskiU period =01d Eed Sandstone of Europe 

 Upper 4 Chemung period 

 Devonian / tt -ij^ 



^ Hamilton period 



Lower / Corniferous period 

 Devonian 1 Oriskany period 



The upper division consists for the most part of arenaceous 

 rocks of great thickness — CatskUl and Chemung; and of black 

 shaley beds — Hamilton, which stretch away into the far west. 



The lower division, consisting of the Corniferous and Onondago 

 Limestones, which have only a thickness of fifty feet, constitute 

 an almost continuous Coral reef, over an area of not less than 

 600,000 square miles, from the state of New York to the 

 Mississippi, and between Lakes Huron and Michigan in the 

 North, and the Ohio river and Tennessee in the South. Professor 

 James Dana * says " the Limestone is Hterally an ancient reef. 

 It contains Corals in vast numbers and of great variety; and in 

 some places, as near Louisville, Kentucky, at the falls on the 

 Ohio, the resemblance to a modern reef is perfect. Some of the 

 Coral masses at that place are 6 or 8 feet in diameter; and single 

 Polyps of the Cyathophylloid Corals had in some species a 

 diameter of 2 or 3 inches, and in one 6 or 7 inches. The 

 same reef-rock occurs near Lake Memphremagog, on the 

 borders of Vermont and Canada, but the Corals have been 

 partly obliterated by metamorphism." The early Devonian, 

 observes our author, was the Coral period of the ancient 



* Text Book of Geology, p. 105. 



