Geology and Mineralogy. 69 



and oil, and is well exhibited on a map facing page 48, giving the 

 depths at which the Trenton limestone lies buried. Along the 

 Ohio near Cincinnati the depth is- about 300 feet above tide-level, 

 and 150 miles east of north/- 20 miles from Lake Erie, it is near 

 500 miles below it. Tide-level is passed by its upper surface 

 about 40 miles north of Cincinnati. The mean pitch for the 

 whole 150 miles is 1 to 1000. For the first 40 miles it is 1 : 700 ; 

 for the next 75 miles, Eaton to Lima, or 85 miles, from Eaton to 

 Beaver Dam, nearly 1 : 1000. About the Beaver Dam region, a 

 bending up of the beds of the anticline occurs, and there is a rise in 

 the next 24 miles from 310 to 350 feet below tide-level ; and the re- 

 gion at this point is that of Findlay. A dozen miles beyond 

 Findlay the northern dip of the anticlinal is resumed, but its po- 

 sition is changed a little to the eastward of the previous course ; 

 and in the next dozen miles there is a fall of 50 to 90 feet, or to 

 400 feet below tide-level ; but 3 miles beyond this, at Bowling 

 Green (22 miles from Lake Erie), the depth obtained is only 387 

 feet. Nearer the lake, in Ottawa County, the dip down increases 

 much, the depth of the Trenton at Oak Harbor being 724 feet. 

 East or west of the axial region of the anticline the dip is larger ; 

 westward, in the northwestern corner of the State, the depth be- 

 comes 1000 feet to 1500 or beyond, and the same is true to the 

 eastward, the depth below tide-level at Port Clinton, only 14 

 miles from Oak Harbor, being 1079 feet below tide-level, show- 

 ing a dip exceeding 1 in 300 ; and along the region southward to 

 the Ohio, the depth increases and the overlying rock is mostly 

 an Upper Devonian shale. 



These levels are here cited because, as Professor Orton points 

 out, they have a bearing on the gas-producing character of the 

 region. Findlay is the center or most productive part of the 

 Trenton limestone gas-supply ; and, as is above shown, it is situ- 

 ated, like other localities of gas-production in western Ohio, along 

 the axis of the anticlinal; but it has the advantage of being situ- 

 ated over the summit of an upward bend in the axial region. 

 This summit region extends northward for 10 or 12 miles, so as 

 to include also Yan Bnren and Bairdstown. The Findlay gas- 

 wells — of which 16 out of 17 bored are productive — yielded in 

 1886 at the rate of 20,000,000 to 25,000,000 cubic feet of gas per 

 day ; and one, the Karg well, is credited with half the whole 

 amount. The depth to which the stratum of Trenton limestone 

 is usually penetrated is only 15 to 25 feet, though occasionally 

 50 to 60 ; much below this, comparatively little is obtained ; and 

 the depth from the surface of the country is 1100 to 1200, so that 

 the expense of boring is small. A well at Yan Buren even ex- 

 ceeds the Karg well ; and one at Bairdstown is not inferior to it, 

 for 9 feet down in the Trenton the supply was 4,000,000 cubic 

 feet per day; at 17 feet, over 12,400,000 cubic feet and the tools 

 " refused to descend deeper, dancing in the well like rubber 

 balls." Bairdstown and Yan Buren, as above stated, are in the 

 same upward bend of the anticline and at nearly the same level. 



