Mar., 1910.] Pennsylvanian Limestones. 91 



Pennsylvania. [U. S. Geol. Sur. Bui. 249, p. 37.] This is clear- 

 ly a better name than Ferriferous and it will doubtless prevail. 

 He has mapped its outcrop in that state and shows it present up 

 the Ohio, the Beaver, and the Mahoning Rivers, and that it is 

 the thick limestone found in the hill tops at Bessemer, Hillsville 

 and entering Ohio at Lowellville. 



It is apparent from this brief review of Pennsylvania geology 

 bearing on this lower group of limestone in that part of Penn- 

 sylvania adjacent to Ohio, that there are but three limestone 

 so far observed. They are the Lower Mercer, Upper Mercer, 

 and Vanport Limestones, the first two being named from out- 

 crops near Mercer, Mercer County, Pennsylvania. 



In Ohio we are indebted very largely to E. B. Andrews, J. S. 

 Newberry, and Edward Orton for our present knowledge of the 

 occurrence, the character, and the strata associated with the 

 limestones considered in this paper. So often have they des- 

 cribed and spoken of them in the Reports of the Ohio Geological 

 Survey that indeed the names of these limestones — Lower 

 Mercer, Upper Mercer, Putnam Hill, and Ferriferous, are quite 

 familiar to every one at all conversant with Ohio geology. The 

 first two and last of these names are of Pennsylvania origin as 

 already noted. The third, or Putnam Hill, is a name of Ohio 

 origin and was given by Andrews in 1869 to a conspicuous stra- 

 tum of limestone typically exposed in the above hill at the 

 foot of which nestles the city of Zanesville. [Ohio Geol. Sur. 

 Rep. of Prog. 1869.] When Andrews named this stratum the 

 other names did not exist in Ohio nomenclature, as it appears 

 only one of the other three limestones was noticed. That 

 stratum has since been considered the Lower Mercer and seen 

 in the river bed at Zanesville. It does not appear, so far as the 

 writer is aware, that these limestones observed at Zanesville 

 were at first even suspected of being the same strata found 

 beyond the Pennsylvania line. Later however these strata were 

 traced northward through Muskingum, Coshocton, Tuscarawas, 

 and Stark Counties, and the Putnam Hill found to be the prin- 

 cipal limestone stratum but apparently disappearing from 

 the section north eastward from central Stark County. The 

 Lower or Blue Limestone, as it is usually called, was named the 

 Zoar Limestone 1878 by Newberry from the typical exposures 

 near Zoar in Tuscarawas County. [Ohio Geol. Sur. Vol. Ill, 

 p. 60.] But this stratum was later regarded as identical with 

 the Lower Mercer in Pennsylvania and the latter having priority 

 the name Zoar is discontinued. 



In his discussion of Coal No. 4 under the head of "The Car- 

 boniferous System of Ohio," Newberry in 1874 states that: 



"Throughout the greater part of the belt of outcrop of the 

 Lower Coal Measures in Ohio, at a distance varying from 20 to 



