GEOLOGY OF THE GEXEVA-0\'1D QUADRANGLES I7 



is little advantage in separating the upper division of this (Mar- 

 cellus) shale from the Hamilton group. The line of separation is 

 nowhere well marked, the change in lithological character being 

 gradual, while some of the fossils continue from one to the other/' 

 On page 187 of that report, in describing the Hamilton group 

 he says: "Along the banks of these lakes (Seneca and Cayuga) I 

 have been able to trace the following subdivisions which hold good 

 over considerable areas but which can not be relied on in every 

 instance. 



1 Dark, slaty fossiliferous shale, which rests directly upon the 

 ]\Iarcellus. . . not very abundant in fossils. 



2 Compact calcareous blue shale often passing into an impure 

 limestone, thin and worthy of notice only from being somewhat 

 persistent and marking the point of separation between two or more 

 important shaly masses. 



3 An olive, or often bluish fissile shale, resting upon the last 

 named mass. 



4 Ludlowville shale. 



5 Encrinal limestone. 



6 Moscow shale." 



The first three of these subdivisions dififer so slightly in both 

 lithologic and faunal characteristics that they have been pretty much 

 lost sight of as such, the loose term " lower Hamilton " having been 

 commonly used for all the beds between the Cardift' and Ludlowville 

 shales. 



The Skaneateles shale, as the term is used in this bulletin, com- 

 prises I, 2 and 3 of the above specified subdivisions. Its estimated 

 thickness here is 200 feet, but owing to the general flatness of the 

 region over which it is the surface rock there are no favorable 

 exposures. The upper layers outcrop along a small stream i mile 

 south of Fayette and the basal layers ^4 ii^i'^ north of that village. 

 The contact with the succeeding Ludlowville shale may be seen in the 

 cliffs at the falls in the lower part of Big Hollow creek 3 miles 

 north of Hayt Corners: in the ravine i'^' miles farther north at top 

 of falls; along Reeder creek, a mile south of \^arick station; and 

 on the shore of Seneca lake north of Dey landing. The upper 

 beds are also well displayed on the west side of Seneca lake in the 

 ravine of Wilson's creek at and below the falls. 



Fossils are less common in the Skaneateles shale than in the 

 higher subdivisions of the Hamilton group, but the collector may 

 expect to find good specimens of the following forms: 



