to the Ohio Shale Problem. 175 



mung) in the wells at Bellaire and Wheeling from 400 feet on 

 beneath the base of the Berea. But I shall not object if my 

 statement that all of the pre-Bedford part in the Wellsville 

 well is p re-Huron is for the present set down as pure assump- 

 tion on my part. Whether the northwesterly thinning of the 

 shale complex in this case is or is not confined to pre-Huron 

 Devonian deposits is of no immediate consequence. Certainly 

 it can have no vital bearing on the determination of a rate of 

 overlap thinning in these formations that may be cited as a 

 desired precedent. However the record is interpreted, the 

 rate is not less than 20 feet to the mile ; and that, considering 

 the great distance, is ample for our purpose. 



As I have said, the rate of thinning increases as we approach 

 the Carter axis. As the first instance, I would cite the wells 

 at Akron and Elyria. In the former the shale complex is at 

 least 1737 feet (Orton, Geol. Survey Ohio, vol. vi, says 1862 

 feet), while in the latter it is but 800 feet. Here, then, the 

 rate is a trifle under 27 feet to the mile. But much greater 

 rates are recorded in the reports of the Ohio Geological Survey. 

 I shall mention only three instances, the first two, as described 

 by Bownocker,* occurring in the Lancaster-Bremen oil and gas 

 field in the central part of the state, the third within the pres- 

 ent limits of the city of Cleveland. \ (1) In 25 miles due 

 southeast from the Buff well, No. 2, in the Pleasantville pool, 

 to the Kennedy well, No. 1, the interval between the Berea 

 grit and the Devonian limestone expands 110 feet (880 to 990 

 feet), making a rate of 44 feet to the mile. (2) In an east-west 

 direction from Lancaster to the Lefever well southeast of New 

 Lexington, a distance of 23 miles, the same interval increases 

 from 630 feet to 1345 feet, that is, 715 feet, giving an average 

 rate of increase of 31 feet per mile. In the first 9 miles, that is 

 from Lancaster to Bremen, the increase is over 34 feet to the mile. 

 Both of these instances lie on the eastern flank of the Carter axis. 

 (3) This concerns differences noted in comparing the logs of the 

 Newburg and Wade wells, the latter being located on Euclid 

 avenue about 5 miles northwest of the former. Deducting differ- 

 ences in altitude of the well heads of the two wells, we find 1225 

 feet of shale in the Newburg well that is strictly comparable 

 to 930 feet in the Wade well. According to these calculations, 

 which have been verified by Professor dishing, there is a dif- 

 ference of 295 feet in thickness of shale between the two wells. 

 Dividing this by 5, the distance in miles between the two wells, 

 gives nearly 60 feet of decrease per mile. 



A low part of the Carter axis is indicated between Ashland 



* Bownocker, J. A. : The Bremen Oil Field, Bull. No. 12, Geol. Survey 

 Ohio, pp. 18-22, 1910. 

 f OrtoD, Edward : Geol. Survey Ohio, vol. vi, pp. 25-352, 1888. 



