Pbosser — Hamilton and Chemung Series. 



Ill 



X\ IFI B*. Immediately above the Hamilton shales which have just 

 been described, is an argillaceous limestone eighteen feet in thickness forming 

 a cascade in the run. In places the limestone is quite shaly and very 

 siliceous, while other portions of the exposure are strongly calcareous. 

 An analysis by Mr. John B. Anderson of a sample from one of the calcareous 

 layers gave the following result: 



Fe 3 4 7.85 per cent. 



Si 32.59 " 



CaCo 8 57.77 " 



MgCo 3 4.28 " " 



Total 102.49 " 



This is the Tully limestone. it weathers in a manner similar to the 

 outcrops farther up Pleasant brook above Upperville, and in the hills near 

 De Ruyter. This outcrop of the Tully limestone is about two miles southeast 

 of its previously farthest eastern known exposure, which is on the hillside a 

 short distance below Upperville, Smyrna township. 1 



XVITIf)*. Above the limestone for twenty feet in the brook, there 

 are no outcrops and then grey to bluish, arenaceous unfossiliferous shales 

 appear. There is scarcely any trace of the black Genesee slates along the 

 brook, even as loose pieces. However, that part of the brook without out- 

 crops, between the arenaceous shales above and the limestone below, is the 

 place for the Genesee slate, consequently it maybe represented at this locality 

 and he covered by soil. The blue arenaceous shales are fairly exposed along 

 the upper part of the brook on the highway and in the field above, with a 

 thickness of 140 feet. Then for 130 feet higher, forming the upper portion 

 of the slope, there are no outcrojw, all the rocks being covered by the soil. 

 The tine blue shales are well exposed for some distance along the highway, 

 on the slope, but a hasty search revealed no fossils. Part of the shales are 

 very smooth and split into thin pieces, and these are well show n in a small 

 brook by the side of the highway on the opposite side of the hill. At this 

 place no fossils were found. 



These bluish, unfossiliferous shales, at least 140 feet in thickness, belong 

 in the Portage formation and correspond to the low er part of it, as exposed in 



1 The outcrop near Upperville was described by the writer in 1887. (See Proceedings American Association Advancement of 

 Scieuce, Vol. XXXVI, p. 210.) Also by Prof. S. G. Williams in the Sixth Annual Report State Geologist [New York], p. 18. 



The calcareous strata in eastern Pennsylvania which the Pennsylvania geologists correlated with the Tully limestone of New 

 York (see Pennsylvania Geological Survey, Summary Description (ieology Pennsylvania, Vol. II, 1892, p. 1818, with map of area 

 on p. 1314), has been shown by the writer to belong considerably lower in the Hamilton formation. (See Bulletin United States 

 Geological Survey, No. 120, 1894, pp. 7, 72.) 



