4 GEOLOGY OF OHIO. 



1 t, . 

 18. Glacial drift to 550 feet. J- |j £ 



J or 



17. Upper Barren Coal Measures 



16. Upper Productive Coal Measures 



15. Lower Barren Coal Measures 



14. Lower Productive Coal Measures 



13. Conglomerate Group 



500 ' 



200 " 



' 1 C 

 ■ 1 - 5 * 



500 " 

 250 " 



t. O 3 



r A o 



250 ' 



1 -Jo 



25 " 

 500 " 



500 " 



; 1 A 



II * 

 i T. 3 



l a o 



a 



12. Sub-carboniferous limestone, Maxville, Newtonville, etc., 



f lie Logan Group 0-350. ] 



I lid Cuvahoga Shale, 150-450. | 500 / 

 11. Waverly Group -j lie Berea Shale 20-50. f to 



| lib Berea Grit 5-160. | 800" 



L la Bedford Shale 50-150. j 



j 10c Cleveland Shale. ) 

 10. Ohio Shale. 1 10b Erie Shale. L 250 to 3,000 feet... 300 



( 10a Huron Shale. J 



9. Hamilton Shale (Olentaugy Shale?) 25 " g 



8. Devonian Limestone, Upper Helderberg or Corniferous, ^ 



including West Jefferson sandstone 75 " J 



7. Lower Helderberg limestone, or Waterlime, including Syl- "] 



vania sandstone, 50 to 600 feet 500 " d 



f 6d Hillsboro sandstone 30 " | ■£ 



I 6cGuelphorCedarvillelimestone,50-200, 150 " | ,5 



6. Niagara Group. -] 6b Niagara limestone 50 " ;- 'ft 



| 6a Niagara Shale, including Davton lime- u 



L stone, 5 to 100 100 " & 



5. Clinton Group, in outcrop, 20 to 75 feet; undercover, 75 to 150. 50 " | £* 



4. Medina shale, in outcrop, 25'; under cover, 50 to 150 75 " j 



3. Hudson River Group, 300' to 750' 750 



2. Utica Shale, not seen in outcrop, but 300 feet thick under j & g 



cover in northern Ohio 300 " ! ^3 



1. Trenton limestone, seen onlv in Pt. Pleasant quarries, if at I t4*3 



all, in the state 0-50 " ' M 



The Trenton Limestone. 



The Trenton limestone is one of the most important of the older for- 

 mations of the continent. It is the most widespread limestone of the 

 general scale of the country. It extends from New England to the 

 Rocky Mountains, and from the islands north of Hudson's Bay to the 

 southern extremity of the Allegheny Mountains in Alabama and Georgia. 

 Throughout the vast region it is found exposed in innumerable out- 

 crops. As it decays, it gives rise to limestone soils which are sometimes 

 of remarkable fertility; as, for example, those of the famous Blue Grass 

 region of central Kentucky, which are derived from it. It is worked for 

 building stone in hundreds of quarries, aud it is also burned into lime 

 and broken into road metal on a large scale throughout the regions where 

 it occurs. 



But widespread as are its exposures in outcrop, it has a still wider 

 extension under cover. It is known to make the floor of entire states, in 

 which it does not reach the surface in a single point. 



It takes its name from a picturesque and well known locality in 

 Trenton township, Oneida county, Xew York. The small river, known 



