292 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



The surface occupied by this formation in western Canada is probably between 6,000 and 

 7,000 square miles. A great part of this however is deeply covered by drift, so that the exposures 

 are comparatively few. * * * 



The generally small dip of the strata and the frequent occurrence of slight undulations 

 render it very difficult to find the succession of the beds, or to determine with accuracy the 

 whole thickness of the Corniferous formation. The great extent occupied by it in western 

 Canada, however, makes it probable that it must be much more considerable here than in New 

 York. In the townships of Woodhouse and Townsend, where there are frequent exposures, the 

 breadth at right angles to the strike is upward of 10 miles. The fall of the surface, in that 

 distance, is estimated at 140 feet; so that if the average slope does not exceed 30 feet in a mile, 

 there would here be a thickness of about 160 feet of the Corniferous limestone. The strata 

 which in Michigan are considered as the equivalents of this formation have, according to Prof. 

 Winchell, a thickness of about 350 feet; so that it would appear that the thickness gradually 

 augments to the westward. 



The formation enters Canada from New York, nearly opposite Buffalo, and is traceable in 

 a narrow belt along the shore of Lake Erie, resting on the Oriskany sandstone, or, where this is 

 wanting, on the Waterfime series. * * * Some portions abound in chert, which forms 

 beds of from 1 to 4 inches or exists in nodules like flints in the limestone. Many of the beds 

 contain sificified organic remains. These in some locafities, as in North Cayuga and at Port 

 Colborne, are found weathered out and loose, in great^ abundance, at the surface of the ground. 

 Some of the beds are httle more than an aggregate of sUicified organic remains, with so little 

 calcareous matter that the whole mass coheres, after the carbonate of fime has been dissolved 

 out. * * * 



To the west of the Grand River, in the counties of Haldimand and Norfolk, the Corniferous 

 limestones are often seen resting on the Oriskany formation and forming smaU eminences, which 

 present escarpments, with the sandstone at their base. These limestones are here of a drab 

 color and abound in chert. * * * 



Higher in the series, along the same fine of country, blue limestones-, sometimes to the 

 amount of 20 feet, with gray beds in lesS volume, are associated with cherty layers, and inter- 

 stratified with bands of a drab-colored limestone. * * * 



The hmestones of this formation are all more or less bituminous, and bitumen exists in 

 many of them in a fiquid form, as petroleum or rock oil, filling the cells of the corals and other 

 fossils. The corals often prevail in distinct bands, some of which wiU be saturated with the oil 

 while those above and below will have little or none. In working Mr. Horn's quarry, which has 

 already been mentioned, on the thirteenth lot of the second range of Bertie, the oil is seen to 

 impregnate particular beds, which are in great part made up of the remains of a species of 

 Heliophyllum. These corals, in various attitudes, are arranged in bands varying in breadth 

 from 3 to 6 inches; and in their open cells the petroleum is lodged. The intermediate parts of 

 the rock, which contain no oil, are composed of a mass of broken organic remains, chiefly encri- 

 nites, while in the coral-bearing beds these comnainuted crinoids serve as a paste to fill up the 

 interstices among the corals. 



Logan defines the stratigraphic limits of the Hamilton formation of Ontario as 

 follows : 



In the western part of Canada we have not been able to distinguish either the Marcellus 

 shales or the Tully limestones from the Hamilton group, and we shall therefore, in describing the 

 rocks of that region, include under the name of the Hamilton formation all the strata between 

 the Corniferous limestones and the Genesee shales. This formation occupies the lowest portion 

 of the saddle-shaped depression noticed in the previous chapter as crossing the peninsula from 

 Lake Erie to Lake Huron and separating the Corniferous formation into two areas. The space 

 thus occupied is very much covered by drift and the contact between the Corniferous and 

 Hamilton formations has not yet been seen, so that it is not easy to assign their precise strati- 

 graphical place to the exposures which are met with. 



