302 



GEOLOGY OF OHIO. 



have been undermined and dropped below their proper horizon ; glacial 

 striae on their surface south 35° east. 



Near Plymouth village, the Berea crops out on the banks of the stream, 

 showing massive rock about twelve feet in thickness, nearly horizontal, 

 and of good quality. At Edgar Bovier's quarry, just east of the village, 

 the rock is in thin horizontal layers, becoming thicker as the opening is 

 carried downward; color, grayish blue, many of the layers affording a 

 sharp grind-stone grit. Here, and at openings further north on the river, 

 streaks of coaly mat+.er, derived from plants, are not infrequent in the 

 Berea. The rock is here unaffected by glacial action, but the disturbance 

 becomes very marked further down the river. At G. Graham's quarry, 

 in Greenfield township, the rock dips 13J° south-westerly, with the line 

 of strike south 35° east, is in very even layers, all finely ripple-marked, 

 some with that puzzling mammary surface, probably caused by the action 

 of eddies where " two seas met " on the old ocean shore. Following down 

 the stream the dip increases in fifty rods to 37^°, then diminishes to 10J°, 

 increasing again till the layers become almost vertical (standing at an 

 angle of 75°), with the line of strike south 29° east. 



The following is a section of the Berea grit and the rocks exposed 

 below it at this place : 





1. Drift. 



2. Berea, evenly bedded 



3. Turtle-backs 



4. Sandy shale, alternating -with argillaceous shale 



5. Evenly bedded sandy shale 



6. Argillaceous shale, with bands of hard rock 



Ft. 



25 to 30 



3 

 6 

 8 



26 





7. Turtle-backs, in three layers 8 to 10 



8. Evenly bedded shale 8 



9. Turtle-backs, in soft argillaceous shale 3 



10. Bhaly sandstone, waved and ripple-marked 20 



11. Hard sandstone, with thin layers of soft shale 5 to 6 



12. -Blue black shale . . . 



13. Shaly sandstone ... 



14. ArgUlaceous shale . 



20 



2 

 16 



