go The Ohio Naturalist. [Vol. X, No. 5, 



"* * * * in the neighborhood of Xew 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. ISO.] 



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 strattmi: 



"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 writer further says that in the southeast part of 

 Shenango Township (the southwestern township of Mercer 

 County and adjacent to Ohio), the Mercer Loiver 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. Prodiictus, 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 Lowell ville, 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 wa3^ He renamed it the Vanport Limestone from typi- 

 cal outcrops at Vanport on the Ohio River in Beaver County, 



