PALEOZOIC TIME — DEVONIAN. 581 



SO that the presence of Corniferous rocks is doiibtful. The recent map of 

 the Canadian survey makes a Devonian belt (with Carboniferous beds) 

 to come down from the far north, along by the summit of the Kocky 

 Mountains, into the United States. 



The Corniferous limestone in some places abounds in mineral oil. The' 

 oil wells of Enniskillen, western Canada, are from this rock, according ta 

 T. S. Hunt (1863) ; large areas are covered with the inspissated bitumen. 

 At Eainham, Canada, on Lake Erie, shells of Pentamerella arata are some- 

 times filled with the oil ; and in other localities Corals of the genera 

 Heliophyllum and Favosites have their cells full, in some layers of thj 

 limestone, while empty in other layers. 



The facts, with regard to the distribution of the Devonian formations in North 

 America, the history of geological discovery in connection with them, their geological 

 relations and distinctive features, are clearly and fully presented by H. S. Williams, in 

 Bulletin No. 80 of the U. S. Geol. Survey, and partly from personal observation. 



Interior Continental and Appalachian region. — The Cauda-gaUi gritm'New York 

 is a drab or brownish argillaceous sandstone, often shaly and crumbling. From eastern 

 New York it continues along the northwestern boundary of New Jersey, and the eastern 

 of Pennsylvania, where it is a gritty slate, and is in some places 400' to 500' thick. 



The Corniferous limestone in New York consists of two members, — the gray Onondaga 

 limestone, or loicer part, and the darker Corniferous, or upper. But the two alternate 

 with one another, and no distinction is now recognized. The limestone is sometimes 

 oolytic. Its thickness, as found where boring for oil and salt, is commonly 100' to 160'; 

 at Ithaca only 78'. Along the Delaware, south of Port Jervis, N.Y., to the New Jersey 

 boundary, the thickness is about 250' ; the flint nodules are from an inch to a foot in 

 diameter, and often contain shells and remains of Crinoids. 



In Ohio it occurs on both sides of the Cincinnati geanticline, and also along the 

 shores of Lake Erie. On Kelleys and Middle islands, in this lake, the beds have 

 the characters of old coral reefs, like those at the Falls of the Ohio. It corresponds, it is 

 supposed, to the whole Upper Helderberg period ; two divisions are made out, — the 

 lower, named the Columbus, or Sandusky, and the upper, the Delaivare limestone. 



In Missouri, siliceous and sandstone layers altei'nate with the limestone. 



Bocky Mountain and Pacific border regions. — In the Eureka district, the thickness, 

 according to A. Hague, is 8000'; the lower, 6000', limestone (see page 592); and the 

 rest, shales. Lower Devonian fossils exist in the lower part for at least 500', and Upper, 

 in the upper portion ; but no subdivisions could be marked off. The Eureka district 

 appears, therefore, to be the center of one of the extra thick Devonian basins, like those of 

 the Appalachian region, and Gaspe of eastern Canada, on the St. Lawrence Gulf. 

 How far south or north the thick beds continue is not known. To the north, in the 

 Tucubit Mountains, Devonian occurs. 



In Arizona, in the Kanab Caiion (112i° W.), the whole Devonian is only 100' thick 

 (Walcott). 



In the Wasatch region, the " Ogden quartzyte " is referred to the Devonian, by King, 

 who found it at Ogden Caiion 1200' to 1400' thick, at Cottonwood Caiion 1000', and 

 at some points in Middle Nevada 800' to 900'. In the Wasatch Mountains, the lower 

 1400' or more of the overlying Wasatch limestone (7000' thick) is Devonian, it affording 

 fossils of the Upper Helderberg, Genesee, and Chemung. See King, Geol. 40th Far., 

 page 236, 



In the Laramide range of the southern part of British America occur 1500' of Devonian 

 limestone (McConnell). 



