1881.] 259 [Stevenson. 



12. Shale 80' 



VS. Limestone 5' 



14. Shale 75' 



15. Limestone 20' 



16. Shale 150' 



17. Limestone 5' 



18. Shale 60' 



19. Limestone 80' 



20. Argillaceous limestone 60' 



21 Granular to argillaceous limestone 100' 



23. Argillaceous limestone 35' 



23. Concealed 25' 



24. Granular limestone 30' 



25. Granular limestone 25' 



Silicious Group. 



26. Cherty limestone 70' 



27. Granular limestone 35' 



28. Cherty massive limestone 65' 



29. Concealed 10' 



30. Limestone 30' 



31. Concealed 50' 



32. Limestone and shale 40' 



33. Massive limestone 125' 



34. Shales and thin limestones 90' 



35. Limestone 80' 



36. Calcareous shale 35' 



37. Limestone 25' 



38. Shales, sandstones and calcareous grits 100' 



Total, Mountain Limestone group, 2270' ; Silicious group, 755' 

 These thicknesses are all estimated, except those from No. 7 to No. 15. 

 No. 1 was seen in the gorge of Wolf creek ; Nos. 2 to 20 inclusive were 

 obtained along Abraham creek ; Nos. 21 to 30 inclusive are exposed in 

 the river bluff below the railroad bridge ; and Nos. 31 to 38 are shown in 

 the railroad excavations along the river bank. 



No. 1 shows much the same features as in Pennington's gap, as well as 

 along the road leading south-east from Moccasin gap. Its base is reached 

 at the forks of Abraham's creek, at say one mile from the North Fork of 

 Holston river. This mass forms the left hand wall of Wolf Creek gorge, 

 through which the railroad passes for several miles. Here, doubtless, a 

 detailed section could be obtained, but the wall is very steep and its ascent 

 would be attended with danger. The greater part of the rock is a more or 

 less ferruginous calcareous grit, much of wliich is dark blue on the fresh 

 surface ; but the iron and lime are easily leached out, so that, on exposure, 

 fragments become "rotten" to a depth of several inches. Some portions 

 are very fine-grained and hard, so as to be fit for grindstones ; these are 



PKOC. AMER. PHILOS. SOC. XIX. 108. 2g. PRINTED FEBRUARY 26, 1881. 



