fable depths in the underlying limestones of the T 
tas € supplies from this region have not ee ae 
abundant, yet from one of the wells just mentioned, 120 bar- 
T. 8. Hunt on the Geology of Southwestern Ontario. 361 
gical Report for 1866, may be mentioned a well at Oil Springs, 
in Enniskillen, which was sunk toa depth of 456 feet from 
the surface, and seventy feet in the solid limestone beneath the 
Hamilton shales, before meeting oil, while in adjacent wells 
supplies of petroleum are generally met with at varying depths 
in the shales. In a well at Bothwell, oil was first met with at 
420 feet from the surface, and 120 feet in the Corniferous lime- 
stone, while a boring at Thamesville was carried 332 feet, of 
which the last thirty-two feet were in the Corniferous lime- 
_ Stone. This well yielded no oil, until, at a depth of sixteen feet 
in this rock, a fissure was encountered, from which, at the time 
of my visit, thirty barrels of petroleum had been extracted. 
At Chatham, in like manner, after sinking through 294 feet of 
shales, oil was met with at a depth of fifty-eight feet in the 
_ underlying Corniferous limestone. 
We also find oil-producing wells sunk in districts where the 
formation overlaid by a portion of the Corniferous. At a dis- 
_ fal barrels of petroleum. Again at Tilsonburg, where the 
and their probable importance as sources of petroleum, was 
first pointed out by me in 1861. The conditions under which 
oll occurs in these limestones in Ontario, are worthy of notice, 
- ‘Masmuch as they present grave difficulties to those who main- 
- tain that petroleum has been generated by an unexplained pro- 
— 8s of distillation going on in some underlying hydrocarbona- 
ales, but petroleum has been found only in fissures at eo 
