THE NIAGARAN FORMATIONS OF WESTERN OHIO 349 



Thickness 



Total 

 Thickness 

 No. Feet Inches Feet Inches 



21. Springfield dolomite. — Buff-colored, rather thin, 

 layers of even-bedded dolomite. The layers 

 vary in thickness from 2 to 8 inches and the 

 majority of the layers are probably from 4 to 6 

 inches thick. No one of the exposed layers is 

 blue. Fossils, as Pentamerus oblongus Sowerby, 

 and corals are common and certain layers con- 

 tain numerous specimens of Pentamerus ob- 

 longus. This zone, with its thin even beds of 

 buff color, has clearly the lithologic appearance 

 of the Springfield dolomite 10 6 106 1 



20. Bluish-gray, weathering to a buff color, rather 

 compact, slightly porous, dolomite which gener- 

 ally splits into two layers 1 a 95 7 



19. Bluish-gray, somewhat mottled, layer which 



contains but few fossils io£ 94 6\ 



18. Bluish-gray layer, fairly compact, in part sub- 

 crystalline, with some small holes and contain- 

 ing large numbers of Pentamerus oblongus 

 Sowerby. On account of the large number of 

 fossils this zone may be called a Pentamerus 

 layer and clearly belongs in the Springfield 

 dolomite 10 93 8 



17. Mottled zone.— Massive layer of bluish-gray 

 dolomite marked with large, irregular-shaped 

 spots of light-gray color, so that the entire sur- 

 face has a coarsely mottled color. It has a 

 porous structure with medium-sized cavities. 

 It contains some fossils, as, for example, cup 

 corals and crinoids, with an occasional specimen 

 of Pentamerus. At the base is a stylolites part- 

 ing 7 2 92 10 



16. Laurel limestone. — Lithologically like lower 

 layers, thickness varying from 9 to 10 inches, 

 more porous in upper 4 inches, with small and 

 larger holes. Some fossils, as a cup coral and 

 Pentamerus ? 95 =±= 85 8 



15. Bluish-gray, somewhat porous, limestone. A 



cup coral was noted 10 84 io| 



14. Layer of light-gray mottled with dark-gray, 

 fairly compact, limestone, varying in thickness 

 from 12 to 13 inches 1 |± 84 § 



