Mercer Limestone in Newark-Zariesville Region 299 



shale overl^dng the limestone, however, carries the same pelecy- 

 pod fauna as the shaly limestone farther northwest. The one 

 pelecypod obtained from the limestone in this vicinity w^as col- 

 lected at the section studied farthest northwest, where the lower 

 part of the limestone is somewhat shaly and softer than in any 

 of the other exposures. The most conspicuous fossils in the lime- 

 stone about Fultonham are the large crinoid segments with pen- 

 tamerous centers. The organic part of the segments has been re- 

 placed by calcite, which presents quite a contrast to the dark 

 blue limestone surrounding the segments and filling the centers. 

 Crinoid stems several inches long are not uncommon, and occa- 

 sionally one is found as much as two feet in length. 



SOMERSET 



Southwest from Fultonham the Mercer limestone shows a tend- 

 ency to become thicker, and in the cut along the Baltimore and 

 Ohio Railroad south of Somerset it is exposed with a thickness of 

 4 feet and 8 inches. The limestone here is in one massive la3'er 

 with the upper part flinty in places, and is dark blue or almost 

 black in color. The lower part of the limestone is very fossilif- 

 erous, showing a great variety of species. In general appear- 

 ance the limestone is not unlike that at Fultonham; but it breaks 

 much more easily and weathers somewhat shaly, in these respects, 

 as well as in fossil contents, more closely resembling the limestone 

 at Bald Knob and Flint Ridge. 



Above the limestone a few fragments of very thin brittle black 

 shale were found, which contained very small gasteropod shells. 

 Below the limestone is a layer of black bituminous shale w^hich 

 is more coaly toward the top; and below this is a fire clay. 



The following collection of fossils was made from the limestone: 



FeuesteUa shuniardi Prout 

 Septopora hiserialis Swallow 

 Prismopora sereata Meek 

 Orbiculoidea convexa (Shumard) 

 Orthothetes crassus (Meek and Hayden) 

 Chonetes mesolohus Norwood and Pratten 



