256 PALEOZOIC TIME. 



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1. The Cauda-galli grit is, in New York, a drab or brownish argillaceous sandstone,. 

 or grit, often shaly and crumbling. In New Jersey, it occurs along the northwestern 

 boundary, and also on the eastern borders of Pennsylvania, as a dark compact gritty 

 slate, and has a thickness in some places of 400 feet. 



2 The Schoharie epoch, if represented in the rocks of the Interior basin, is so by 

 limestone referred to the Corniferous epoch. 



3. The Corniferous limestone, in New York, is dark grayish, and occasionally black ; 

 in the Interior basin, it is usually light-gray, drab, or buff. 



(a) Interior Continental basin. In New York, the thickness of the limestone seldom 

 exceeds 20 feet for the Onondaga, and 50 for the Corniferous. The limestone forma- 

 tion has been recognized in Ohio, along the shores of Lake Erie, in Michigan, Indiana, 

 Illinois, Kentucky, Wisconsin, Iowa, Missouri, and other parts of the Mississippi basin : 

 but the subdivisions above mentioned are not distinguishable. In the Michigan penin- 

 sula, the thickness is 354 feet (Winchell); in Ohio, 60 feet; in Iowa, 50 to CO feet 

 (Hall); in Missouri, from a few feet to 75. The upper part of the limestone in Illinois- 

 is regarded by Worthen as of the Hamilton period. 



The upper layers of the rock, which are usually dark grayish in New York, are 

 nearly black on the Niagara. In some localities west of New York, the rock is oolitic. 

 The hornstone of the Corniferous beds is often left in rough projecting masses, where 

 the limestone portion has been worn away by the action of water. In Missouri, siliceous 

 and sandstone layers alternate with the limestone. These rocks outcrop also in western. 

 Canada, north of Lake Erie. 



(b.) Appalachian region. — This formation extends from New York into New Jersey, 

 where, in the northwestern part of the State, it has a thickness of 500 feet. It has not 

 yet been distinguished among the rocks of Pennsylvania, except northwest of the Kit- 

 tatinny Mountain, between the Delaware and Lehigh Rivers. 



(c. ) Eastern Border region. — At Owl's Head, on Lake Memphremagog, near the 

 northern borders of Vermont, the coral-reef rock is overlaid by mica schist; and, 

 although it is partially metamorphic, many of the specimens of fossils are tolerably per- 

 fect. Among the species, Billings has recognized Syrinyopora Hisinyeri B., Favosites 

 basaltica Goldf., Diphyphyllum stramineum B., and Zaphrentis yiyantea Lesueur. Be- 

 sides these, according to Hitchcock, Atrypa reticularis has been identified by Hall. 



The limestone at Bernardston, Mass., containing large crinoidal stems, described on 

 cage 237, under the Lower Helderberg period, may possibly be of the Corniferous 

 or Upper Helderberg period. At Littleton, New Hampshire, there is a similar lime- 

 stone, containing corals like those of Lake Memphremagog; and conformable with 

 it are beds of quartzy te and other rocks : the fossils are referred to the Corniferous 

 period by Billings. Between Littleton and Bernardston extends a strip of schistose 

 or slaty rocks, in some places calcareous, and often staurolitic, called by Hitchcock the 

 Coos Group, which are either Lower or Upper Helderberg. 



Between northern Vermont and Cape Gaspe - , there are many localities of Devonian. 

 fossils. One locality, given by Logan, is on the Chaudiere River, where there occur, 

 besides Favosites Gothlandica and F. basaltica, the species Syrinyopora Hisinyeri, 

 Diphyphyllum arundinaceum B., a small Productus resembling a Corniferous species, a 

 Zaphrentis, Spirif er duodenariusH., S. yreyarim Clapp, S. acuminatus'R., a Cyrtina like 

 C. rostrata H., etc. Other localities occur at Dudswell and on Famine River. At Cape 

 Gaspe\ the upper part of the 2,000 feet of limestone contains Oriskany fossils (p. 243), 

 but none indicative of the Corniferous period. 



Economical Products. 



The limestone of this period in some places abounds in mineral oil. The oil wells of 

 Enniskillen, Western Canada, are traced to this rock by Hunt ; large areas are there 

 covered with the inspissated bitumen. At Rainham, Canada, on Lake Erie, shells of 

 Pentamerus aratus are sometimes filled with the oil: and, in other localities, corals of 

 the genera Heliophyllum and Favosites have their cells full, in some layers of the lime- 



