54 THE CANADIAN NATURALIST. [Vol. vi. 



may be represented among tlie metamorphic rocks of Grand 

 Manan. I also incline to this opinion (more particularly as 

 regards the strata first described between Whale Cove and Pette's 

 Cove as compared with those on the coast and islands southward 

 of the latter,) but think that neither will be found to be more 

 recent than the earliest Primordial Silurian. 



The accompanying map is a copy of the Admiralty chart of 

 Grand Manan, slightly modified to show the position and extent 

 of its geological formations. 



ON THE OIL-BEARING LIMESTONE OF CHICAGO. 



By T. Sterry Hunt, LL.D., F.E.S. 



(Read before the American Association for the Advancement of Science,, at Troy, 



August, 1870.) 



When in 1861,^ I first published my views on the petroleum 

 of the AYest, I expressed the opinion that the true source of it 

 was to be looked for in certain limestone formations which had 

 long been known to be oleiferous. I referred to the early ob- 

 servations of Eaton and Hall on the petroleum of the Niagara 

 limestone, to numerous instances of the occurrence of this sub- 

 stance in the Trenton and Corniferous formations and, in 

 Gaspe, in limestones of Lower Helderberg age. Subsequently, in 

 this Journal for March, 1863, and in the Geology of Canada, 

 I insisted still farther upon the oleiferous character of the 

 Corniferous limestone in south-western Ontario, which appears 

 to be the source of the petroleum found in that region. I may 

 here be permitted to recapitulate some of my reasons for conclud- 

 ing that petroleum is indigenous to these limestones, and for 

 rejecting the contrary opinion, held by some geologists, that its 

 occurrence in them is due to infiltration, and that its origin is to 

 be sought in an unexplained process of distillation from pyroschists 

 or so-called bituminous shales. These occur at three distinct 

 horizons in the New York system, and are known as the Utica 

 slate, immediately above the Trenton limestone, and the Mar- 

 cellus and Genesee slates which lie above and below the Hamilton 

 shales, the latter being separated from the underlying Corniferous 

 limestone by the Marcellus slate. 



* Montreal Gazette, March 1, and this Journal, July, 1861. 



