1869.] HUNT — GEOLOGY OF SOUTH-WESTERN ONTARIO. 15 



elusions regarding this formation in Ontario. In Wayne county, 

 New York, the Salina formation has a thickness of from 700 

 to 1,000 feet, which, to the westward, is believed to be reduced 

 to less than 300 feet, where the outcrop of this formation, crossing 

 the Niagara river, enters Ontario. 



At Tilsonburg, ninety miles west from Buffalo, borings 

 have shown the existence of the Corniferous limestone directly 

 beneath about forty feet of clay, while two miles to the south-west 

 it is overlaid by a few feet of soft shales, probably marking 

 the base of the Hamilton. From a depth of 100 feet in the 

 limestone, at Tilsonburg, a flowing well was obtained, yielding an 

 abundance of water, and a considerable quantity of petroleum. 

 This boring was subsequently carried 854 feet in the rock, which 

 at that depth was a dolomite. Numerous specimens from 

 the upper 196 feet were of pure non-magnesian limestone ; but 

 below that depth dolomites, alternating with pure limestones, 

 were met with to the depth of 854 feet, from which salt water was 

 raised, marking, it is said, from 35° to 50° of the salometer. 

 The well was then abandoned. We have here a boring traversing 

 854 feet of solid strata, from what was, probably, near the summit 

 of the Corniferous, without reaching the marls which form 

 the lower part of the Salina formation. 



In a boring at London, where the presence of the base of the 

 Hamilton was marked by about twenty feet of gray shales, 

 including a band of black pyroschist, overlying the Corniferous, 

 600 feet of hard rock were passed through before reaching 

 soft magnesian marls, which were penetrated to the depth of 

 seventy-five feet. Specimens of the boring from this well, 

 and from another near by, carried 300 feet from the top of the 

 Corniferous, show that pure limestones are interstratified with the 

 dolomites to a depth of 400 feet. At Tilsonburg a pure 

 limestone was met with at 524 feet from the top. 



At St. Mary's, 700 feet, and at Oil Springs in Enniskillen, 595 

 feet of limestone and dolomite were penetrated, without 

 encountering shales, while in another well near the last, soft shaly 

 strata were met with at about 600 feet from the top of the Corni- 

 ferous limestone, there overlaid by the Hamilton shales. It thus 

 appears that the united thickness of the Corniferous formation and 

 the solid limestones which compose the upper part of the Salina 

 formation, is about 600 feet in London and Enniskillen, and 

 farther eastward, in Tilsonburg and St. Mary's, considerably 



