STRATIGRAPHY OF FOSSILIFEROUS MEMBERS 97 



Jackson and Vinton Counties. The Upper Mercer ore is also 

 found in Jackson County and geologic sections showing its relation to 

 other members of the Potts ville formation are given under the discus- 

 sion of the Lower Mercer member. In Vinton County the* ore is like- 

 wise present, although the limestone phase below is well developed and 

 becomes of more stratigraphic importance than in the counties to the 

 south. In Elk Township, three miles southwest of Me Arthur, black 

 shaly limestone from the Upper Mercer horizon contains specimens of 

 Lingula carbonaria Shumard in great profusion, but no other fossils 

 were discovered (Locality 60). 



Perry County. Fossils were obtained from the limestone in the 

 shaft of the Straitsville Impervious Brick Co. near New Straits- 

 ville in the extreme southwestern part of the county. The deposit at 

 this locality is hard, dark blue, and moderately fossiliferous. There is 

 considerable doubt, however, whether the limestone belongs to the 

 Upper Mercer or the McArthur horizon (Locality 61). The following 

 fossils were identified: 



Crinoid segments 



Derbya crassa (Meek and Hay den) 



Chonetes mesolobus Norwood and Pratten 



Productus cora d'Orbigny 



Productus semireticulatus (Martin) 



Productus semireticulatus (Martin) var. 



Pustula nebraskensis (Owen) 



Marginifera wabashensis (Norwood and Pratten) 



Spirifer opimus Hall 



Composita subtilita (Hall) 



In Perry County as in Muskingum and Coshocton counties, the 

 Upper Mercer limestone is generally partially or wholly replaced by 

 massive beds of flint, dark to black in color. In the eastern part of 

 Section 3, Clayton Township, where the geologic section below was 

 measured, the flint is partly light gray in color and very sparingly 

 fossiliferous. Samples were collected from the ravine near the road 

 (Locality 62). 



Feet Inches 



Shale and covered 50 



Flint, light .gray, fossiliferous "i T 3 4 



Limestone, very ferruginous [upper Mercer \ " 4 



Covered | 1 



Flint, black, fossiliferous J L 3 



Covered 3 



Coal blossom, Bedford 1 



Clay and shale 16 



Limestone, blue, fossiliferous, Lower Mercer 1 



4 G. B. 25. 



