9° 
The Ohio Naturalist. 
LVol. X, No. 5, 
“ * * * * in the neighborhood of New Castle on the Beaver 
River, another limestone bed, the Mahoning Limestone, 2 feet 
thick, is interposed immediately under the Tionesta sandstone;” 
[Geol. Penn. Vol. II, Part I p. 489.] 
Of the Ferriferous Limestone, which is the first one below the 
Lower Kittanning Coal, he states that it is so called because in 
many localities a valuable deposit of iron ore rests directly upon 
it. At New Castle he says this limestone rests upon the “ Scrub- 
grass Coal-bed,” the latter having a maximum thickness of 20 
inches. (Geol. Penn. Vol. II, Part I, p. 491.] 
In 1875 in his report on Beaver Valley, H. Martyn Chance 
states as follows: 
‘‘Both of the Mercer limestones were seldom seen in one 
locality one or the other generally being absent, and it is Often 
difficult to tell to which of the two the one noted should be re- 
ferred — the upper Mercer Limestone usually occurring at 90 
to 115 feet beneath that stratum.” (Ferriferous limestone.) 
[Sec. Geol. Sur. Pa. Vol. V. p. 189.] 
In his report on Mercer County in 1878 under the head of 
The Upper Mercer Limestone , I. C. White writes as follows con- 
cerning that stratum: 
‘‘ This is the ' Mahoning Limestone of Rogers ’ who recognized 
it on the Mahoning River, but not in Mercer County, where in 
fact it can only be seen at a few localities.” [Sec. Geol. Sur. 
Pa., Rep. Prog. 1878 Q. 0. Q. Geol. Mercer County, p. 36.] 
The same Avriter further says that in the southeast part of 
Shenango Township (the southwestern township of Mercer 
County and adjacent to Ohio), the Mercer Lower Limestone is 
here seen in two layers (a character which it often exhibits), the 
upper one 2 feet thick and the lower one 6 inches. There does 
not appear to be any separating material, not even the thinnest 
shale, but the layers appear to be in immediate contact, and 
both are richly fossiliferous; species of Spirifer. Productus, and 
Crinoids being especially numerous. [Geol. Sur. Q. Q. Q. p. 97.] 
Discussing the ferriferous limestone in his report on Butler 
County, Chance makes this statement of it: 
‘‘In Ohio, except at Lorvellville, on the Mahoning, where it 
exhibits its usual character, it is much thinner than in Pennsyl- 
vania, and, compared to its value in the latter state, is worth but 
little, either as a limestone or as an iron ore carrier. Its outcrop 
enters Ohio near the Mahoning river.” [Geol. Sur. Pa. Report 
of Progress V, p. 142. 1878.] 
In a bulletin prepared by F. G. Clapp and issued by the U. S. 
Geol. Sur. in 1904 on the ‘‘Limestones of Southwestern Pennsyl- 
vania,” the ferriferous limestone is somewhat fully treated in an 
economic way. He renamed it the Van port Limestone from typi- 
cal outcrops at Vanport on the Ohio River in Beaver County, 
