Stevenson.] 



400 



[Feb. 5, 



ture of the agency producing the disturbance was, it is difficult to deter- 

 mine. It cdrtainly was exerted over a broad area, extending in the re- 

 gion examined from the line of the Ellenboro' fault to the Ohio River. 

 Fissures are frequent throughout this area, the most notable one being 

 that containing the Grahamite. This has been fully described by Prof. 

 Fontaine in the American Journal of Science. 



The oil is obtained chiefly from rocks, which I regard as belonging to 

 the Great Conglomerate. The grade, for which this region is particularly 

 noted, is of heavy sjiecific gravity and is known as lubricating oil. 

 Lighter oils are obtained, but occur at a greater depth than the others. 



Appendix. Since writing this paper I have received from Dr. "W. H. 

 Sharp, of Volcano, West Virginia, the records of eighteen borings made 

 in difterent portions of the oil break. A comparison of these leaves no 

 room for doubt that the strata within the break, though apparently hori- 

 zontal, are badly broken up, in many places even dove-tailing or not in- 

 frequently crushed into irregular masses. This is sufficiently evident 

 from the variations in the interval between two well marked strata, — the 

 coal-bed, already mentioned, and a limestone at some distance belosv. It 

 is possible, however, to make an approximate estimate of the thickness 

 of the rocks, for several wells bored at somewhat distant localicies show 

 a close agreement. I give condensed sections of four borings. No. I is 

 near the eastern edge ; No. II is in similar position, but one mile farther 

 south ; Nos. Ill and IV are near the central line of the "break " and 

 were naade on lots 56 and 33 of the Volcanic Company's tract : 



I. 



Coal 3' 



Shale 7'1 



Sandstone 23' 



Dark Shale 63' | 



Gray Sandstone 79' ! 



Light Shale 33' | 



Gray Sandstone 24' i 



Shale and S. S 81' I 



Aren. Shale and L. S. . . 77' J 



Limestone 22' 



Shale 101 



9. 

 10. 

 11. 



12. Sandstone 32 



13. Variegated Shale 388' + 



III. 



1. Coal and Shale 8' 



2. Sandstone 80'"] 



3. Dark Shale 32' | 



4. Gray Sandstone 16' [ 



5. Shale 128' 



6. Sandstone 170' j 



Limestone 6 



Sandstone and some 



Shale 12^ 



'+ 



II. 



1. Coal 3' 



2. Interval not given in de- 



tail, but chiefly Gray 

 Sandstone 233' 



3. Limestone 25' 



4. Shale and Sandstone. ...123' 



5. Sandstone 12' 



6. Variegated Shale 213 '-H 



IV. 



1. C'oaZ and Shale 11' 



2. Sandstone 17 1 



3. Dark Shale 12 



4. Sandstone 58 I 



5. Shale 48 I 



6. Shale and S. S 23 ( 



7. Sandstone 82 



8. Sandstone and S 56 I 



9. Sandstone 42 J 



10. Limestone 17 



11. Sandstone *&c 39 + 



