340 CHARLES S. PROSSER 



Nos. 2 to 24, inclusive, are referred to the Osgood beds, which 

 gives this formation in this section an average thickness of 13 feet. 



Farther west in the series of quarries on the northern side of 

 Ludlow Creek is the one of Otto Ehlers, which in the Miami County 

 report is called the Ellis quarry. 1 The section of this quarry is 

 important in determining the stratigraphy of this region due to the 

 excellent exposure of the shale zone (No. 7 of section) which sepa- 

 rates the Dayton and Laurel limestones. 



Section of the Otto Ehlers Quarry 



TIHCKNESS TmCKNESS 



No. Fee Inches Feet Inches 



21. Laurel limestone. — Three layers at the top of 



the quarry wall which in descending order are 



respectively 4, 7, and 6 inches thick. As 



weathered, these layers are buff-colored and 



fairly compact. The upper part of this zone is 



perhaps above the Laurel limestone 1 5 20 4 



20. Compact layer which is more massive than the 



two immediately below it 10 18 n 



19. More compact layer than that immediately 



underlying it 8 18 1 



18. It splits into 2 or more layers which are similar 



to underlying ones 6 17 5 



17. Compact, light-gray dolomite, weathering to 



buff color and varying from 6 to 7 inches in 



thickness 6§± 16 11 



16. It tends to split at the bottom into 3 layers. . 6 16 4^ 



15. Light-gray dolomite which weathers to buff 



color 3 15 io^ 



14. Shale containing calcareous nodules to shaly 



limestone 3 15 7§ 



13. Light-gray, weathering to buff color, compact 



dolomite 10 15 4^ 



12. Shaly, light-gray dolomite, weathering to buff 



color, from 3 to 5 inches thick 4 ± 14 6^ 



11. Light-gray, argillaceous shale 2 14 2\ 



10. Light-gray, fine-grained dolomite, which splits 



into 3 layers 1 8 14 \ 



9. Light-gray, argillaceous shale 3 12 4^ 



1 Report of the Geological Survey of Ohio, III (1878), 479. 



