140 J. J. STEVENSON — CARBONIFEROUS OF APPALACHIAN BASIN 



a total of about 550 feet, inclusive of some part of the Pennington shales 

 of Campbell and Keith (Shenango). Surmise is dangerous where the 

 gaps are so wide, but the sections seem to suggest that the Bonair and 

 Etna conglomerates come together between Rathbun and Graysville, as 

 they do in the region west from Sequatchie valley, not far from the lati- 

 tude of Graysville, and that the combined mass is thinner. This is the 

 more probable, since northward from Rathbun the escarpment is cut 

 back and all members of the formation thin very rapidly toward the 

 west for several miles from the escarpment. Mr Hayes says that the 

 Lookout diminishes from 510 feet on the escarpment to 260 feet in the 

 Crab Orchard range, only 4 or 5 miles toward the west.* 



Professor Safford's section in the gap through Crab Orchard, about 8 

 miles west from Rockwood, reinforces the suggestion. This locality is 

 midway between Rockwood and Crossville. He finds the " Conglom- 

 erate " 100 to 150 feet thick, with the Sewanee (" Haley's ") coal bed at 

 30 to 40 feet above it, while below the conglomerate there are but 228 

 feet of measures.f 



But, however the conditions may be at Rockwood and southwestward, 

 the Bonair and Etna (Cliff) conglomerates are distinct at Harriman, 12 

 miles northeastward from Rockwood, where the escarpment extends 

 farther toward the east. Mr Hayes gives a short section at Harriman 

 showing an interval of 155 feet between the " Rockwood-Harriman " coal 

 bed and the little bed below the Bonair. About thirty years ago Pro- 

 fessor Bradley compiled a general section north from Harriman, which 

 is of great importance, as it was measured carefully. J It is 



Feet. Inches. Feet 



1. Shales 140 



2. Coal bed 1 6 



3. Shale and sandstone 179 



4. Coal bed 



5. Shale and sandstone 90 



6. Coal bed 1 to 3 



7. Shale and sandstone 110 



8. Coal bed, reported to be 1 



9. Interval 50 



10. Coal bed, said to be 1 6 



11. Interval 193 



12. Heavy bedded sandstone [Corbin] 1 53 



13. Mostly shale '. 320 



14. Irregularly bedded sandstone [Rockcastle].. . 50 to 70 



15. Shale and concealed 180 to 200 



*C. W. Hayes, U. S. Geological Survey folios, Kingston, 1892. 



t J. M. Safford : Geology of Tennessee, p. 389. 



\ F. H. Bradley, quoted by Killebrew and Safford : Resources of Tennessee, 1874, pp. 200, 201. 



