26 NEW YORK STATE MUSEUM 



hard shale, usually from 2 to 5 feet thick. The latter contain large 

 symmetric concretions and septaria, some of which attain a dia- 

 meter of 6 to 8 feet. The formation has a total thickness of about 

 200 feet on the lake shore in the town of Evans and is 165 feet 

 thick in the southeast corner of this quadrangle. Its lower beds 

 appear along Smoke's creek, i^ miles south of Windom 

 and some of the shales and concretions near the middle along a 

 branch of the same stream J mile west of Orchard Park. 



Unlike every other formation represented on this quadrangle 

 except the Bertie waterlime, it becomes thinner toward the east, 

 diminishing at the rate of i^ feet a mile to Naples, Ontario co., 

 where it measures 21 feet. It may be seen at nearly all of the 

 exposures of the Cashaqua shale at and above cascades produced 

 by its superior resistance to the erosive power of the streams. 



Common Portage fossils occur but sparingly in the lighter bands 

 in the western part of the State, and the black shales have been 

 found to contain very few fossils except plant and fish remains and 

 a few conodont teeth. 



