SUCCESSIVE DEPOSITS IN THE APPALACHIAN REGION 415 



uppermost Maysvillian. Here also occurs again the Bryozoan Arthropora 

 schafferi, though it has varieties in lower and higher beds. Finally, 

 Lophospira acuminata (number 3) occurs in the Middle Eichmond of 

 the Cincinnati region. 



If the identifications are correct, and Mr. Collie cites Beecher, Schu- 

 chert, and Ulrich as authorities aiding him in the identifications, we have 

 here an illustration of the impossibility of correlating the Appalachian 

 beds with any of the specific horizons of the Cincinnati region.* Alto- 

 gether, we may class these beds as the equivalent of the Pulaski of New 

 York, and probably as the equivalent of the lower part only, the upper 

 division, together with the Oswego, being here represented by the Bald 

 Eagle conglomerate. 



Farther northeast along the Bald Eagle Eidge, at Mill Hall Gap, the 

 thickness of the basal sandstones seems to have increased somewhat, being 

 901 feet. 21 It consists of 188 feet of hard, massive sandstone immediately 

 below the Eed Juniata, mostly white or speckled with iron, beneath which 

 occur 118 feet of softer sandstones and shales, some of them red. If we 

 add these to the Juniata series, the thickness of the Bald Eagle becomes 

 reduced to 595 feet. They are hard, massive sandstones for the most 

 part, with some greenish gray speckled beds. In many cases the speck- 

 ling is due to decomposed feldspar ; in others to iron pyrites. Finally, in 

 the Bald Eagle gaps of Lycoming County, the formation is reduced to 

 about 75 feet of hard sandstone. 22 This is the northern and eastern ex- 

 posure of the rock in Pennsylvania. In all cases the formation rests on 

 the Hudson Elver group of shales and sandstones, but whether the con- 

 tact is a conformable and gradational one or whether a disconformity 

 and a hiatus exist has not yet been ascertained, largely for lack of satis- 

 factory exposures. I am of the opinion, however, that where found the 

 contact will for the most part be a conformable one, as at Tyrone (Jap, 

 the lower beds grading into the upper. If a disconformity exists, T be- 

 lieve that it is local and small, and such as may be expected when a con- 

 tinental series replaces a marine one. 



Southward the thinning of the Bald Eagle beds is more rapid, fn the 

 main gap entering Milligans Cove of Wills Mountain, the southward 



♦In this connection it may be well to call attention to :i complete shifting of an 

 entire fauna eastward in the Hamilton of New York, occurring beneath the Encrinal or 

 Morse Creek limestone on Lake Erie and above it in the <a>nesee Valley (see Faunas of 

 t.he Hamilton Group of Eighteen Mile Creek by A. W. Grabau, 15th Ann. Report New- 

 York State Geologist, p. :{27tT). Evidently Cinch's curl dismissal of the subject of 

 shifting faunas, so ably expounded by Williams, is due to liis lack of familiarity with 

 such examples. 



31 II, M. Chance: Report G4, Clinton County, p. 120. 



22 F. Piatt: Report G 2, p. LM>. 



