56 THE CANADIAN NATURALIST. [Vol. vi. 



with the iutervention only of a sterile sandstone. The rock-for- 

 mations holding petroleum are not only separated from each other 

 by great thicknesses of porous strata destitute of it, but the dis- 

 tribution of this substance is still farther localized, as I many 

 years since pointed out. The petroleum is in fact in many cases, 

 confined to certain bands or layers in the limestone, in which it 

 fills the pores and the cavities of fossil shells and corals, while 

 other portions of the limestone, both above, below, and in the 

 prolongation of the same stratum, though equally porous, contain 

 no petroleum. From all these facts the only reasonable conclu- 

 sion seems to me to be that the petroleum, or rather the materials 

 from which it has been formed, existed in these limestone rocks 

 from the time of their first deposition. The view which I put 

 forward in 1861, that petroleum and similar bitumen have re- 

 sulted ftom a peculiar " transformation of vegetable matters, or 

 in some cases of animal tissues analogous to those in composition," 

 has received additional support from the observations of Lesley,^ 

 in West Virginia and Kentucky, and from the more recent ones 

 of Peckham.f 



The objection to this view of the origin and geological relations 

 of petroleum, have been for the most part founded on incorrect 

 notions of the geological structure of southwestern Ontario, which 

 has afforded me peculiar facilities for studying the question. In 

 this region, it has been maintained by Winchell that the source 

 of the petroleum is to be sought in the Devonian pyroschists. I 

 however showed in 1866, as the result of careful studies of the 

 various borimrs : first, that none of the oil-wells were sunk in the 

 Genesee slates, but along denuded anticlinals where these rocks 

 have disappeared, and where, except the thin layer of Marcellus 

 slate sometimes met with at the base of the Hamilton shales, no 

 pyroschists are found above the Trenton limestone. Second, that 

 the reservoirs of petroleum in the wells sunk into the Hamilton 

 shales are sometimes met with in this formation, and sometimes, 

 in adjacent borings, only in the underlying Corniferous. Examples 

 of this have been cited by me in wells in Enniskillen, Bothwell, 

 Chatham, and Thamesville, where petroleum has first been found 

 at depths of from thirty to one hundred and twenty feet in the 



* Rep. Geol. Canada, 1866, 240 ; and Proc. Amer. Philos. Soc. x, 

 33, 187. 



t Ibid, X, 445. 



