46 NEW YORK STATE MUSEUM 



lent. Subsequently the formations, which were termed by Vanuxem 

 and Hall Skaneateles shale, Olive shale, Ludlowville shale, Encrinal 

 limestone and Moscow shale, were grouped together under the name 

 Hamilton group and by James D. Dana Hamilton group was made 

 to include the Marcellus shale, Hamilton shale and Tully limestone. 

 We now find ourselves compelled to fall back on the original nomen- 

 clature of the units, and the term Skaneateles shale is here applied 

 to that bed of strata for which the name was originally used by 

 Vanuxem. These rocks have a thickness of 335 feet in this quad- 

 rangle, decreasing toward the west. They are at the base for 20 feet 

 soft blue shales in which fossils are much more abundant than in 

 beds of somewhat similar aspect constituting the Cardiff shale be- 

 low. In the Onondaga valley these are overlain by a compact blue 

 limestone about i foot thick which, in the Bear mountain and other 

 ravines, produces a cascade. Above these limestones the shales are 

 sometimes light bluish gray but mostly quite dark and very soft. 

 Small concretions are abundant in the lower part of the beds both 

 above and below the limestone. Near the top of the shales there are 

 occasional thin lentils of limestone composed of masses of fossils. 



The most favorable exposure of these beds is that in the Bear 

 mountain ravine i mile west of Tully Valley where the entire sec- 

 tion of this division is exposed. Others in the Onondaga valley are 

 in the ravine at Tully Valley ; that east of Cardiff' ; that i mile south 

 of South Onondaga and the Joshua ravine i mile farther west. In 

 the Butternut creek valley along the Delaware, Lackawanna & West- 

 ern Railroad in the vicinity of Onativia and northward and also 

 in the lower part of the Conklin's falls ravine and several others on 

 the east side of the valley to the Jamesville-Pompey Hill road, there 

 are additional outcrops ; and the shales are also to be seen on the 

 north slope of Pompey hill, 25^ to 5 miles southeast of Jamesville. 



The shales at the base of the formation and the limestone contain 

 many brachiopods, specially Spirifer, Productella and Liorhynchus 

 and some cyathophylloid corals. In the upper soft shales the brachio- 

 pods, lamellibranchs, Pleurotomarias, goniatites, trilobites and 

 crinoids characteristic of the Hamilton fauna are distributed un- 

 evenly throughout the beds but nowhere in large' numbers. , 



