230 II. P. II. BRUMELL — GAS AND PETROLEUM IN ONTARIO. 



Onondaga and Lower Hdderberg. — Beneath the Oriskany, when present, 

 and usually directly underneath the Corniferous limestone, is a long 

 series of limestones, dolomites, marls, shales, gypsum, and salt constitut- 

 ing the Onondaga, which for convenience can be made to include the 

 Lower Helderberg. This formation acquires a thickness, in the salt 

 region of Huron county, of at least 1,500 feet, according to the following 

 very accurate record made by Dr T. Sterry Hunt* of a well sunk at 

 Gloderich by Mr Henry Attrill,- of that place: 



/•'( i I. Inrlies. 



Surface deposits 7S U 



Dolomite, with thin limestone layers 278 3 



Limestone, with corals, chert and beds of dolomite 27(3 



Dolomite, with seams of gypsum 24."> 



Variegated marls, with beds of dolomite 121 () 



Rock-salt, first bed 30 11 



Dolomite, with marls toward the base 32 1 



Rock-salt, second bed 25 4 



Dolomite G 10 



Rock-salt, third bed 34 10 



Marls, with dolomite and anhydrite 80 7- 



Rock-salt, fourth bed 15 5 



Dolomite and anhydrite 7 



Rock-salt, fifth bed 13 6 



Marls, soft, with anhydrite 135 G « 



Rock-salt, sixth bed ' G 



Marls, soft, with dolomite and anhydrite lo2 



Total depth . . : 1,517 



As to what is the greatest actual thickness of the formation it is im- 

 possible to say, as data regarding its lower measures are wanting. In 

 none of the records obtained has there been definitely noted the red and 

 greenish shales indicative of the base of the formation in New York state. 

 According to the records of wells sunk for gas in Bertie township, Wel- 

 land county, it has there a total thickness of 390 feet, consisting of gray 

 and drab dolomites, black shale and gypsum, and in a well at Petrolea 

 it was found to be 905 or more feet thick, as follows : 



Limestone, hard, white 500 feet. 



Gypsum SO " 



Salt and shale 105 " 



Gypsum SO " 



Salt and shale 140 " 



The formation may be thicker, as drilling ceased in the salt and shale. 



* Report of Progress, Geol. Survey of Canada, 1S70- 77. 



