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NEW YORK STATE MUSEUM 



for the very characteristic blocks of this rock are quite freely 

 scattered south of the line of outcrop and specially in the east 

 bank of Mud creek. Two miles south of Mertensia the blocks are 

 so common and in such a condition as to indicate very slight 

 removal from place. 



Cardiff shale 



The upper beds, heretofore generally included in the old 

 term Marcellus and termed by Vanuxem the " Upper shales 

 of Marcellus " are finely shown in and about the village of 

 Cardiff, Onondaga co. As we have restricted the former term, 

 it seems best to adopt for the succeeding layers a name derived 

 from these excellent exposures near the typical region, as in 

 Ontario county they are nowhere seen to so good advantage. 



The Stafford limestone is overlain by a series of dark calcare- 

 ous and black slaty shales with thin layers of fossiliferous 

 limestone. Both limestone and shales weather to a light ashen 

 gray on long exposure. So far as the fossil contents are con- 

 cerned they are not essentially unlike those of the darker shales 

 below but the gray aspect of the beds and their much higher 

 calcareous content indicate a distinctive difference, which is 

 readily marked throughout this region. Outcrops of these lay- 

 ers are again very few. The best of them is in the bed and sides 

 of Mud creek at its confluence with Shaffer creek in the north- 

 eastern corner of the town of East Bloomfield. They are also 

 exposed in the upper part of the railroad cut section just south 

 of Padelford station. Directly over the line of the quadrangle 

 to the east is an exposure on the east bank of the Canandaigua 

 outlet below Ohapinville, and here some of the harder layers 

 were at one time quarried for flagstone and used in the 

 village of Canandaigua but they proved to check very rapidly 

 under exposure and wear. For a quarter of a mile this exposure 

 is continued in the bank of the outlet. At no exposure is the 

 entire thickness of this bed revealed. The heaviest mass of 

 material shown at any one place is in the section on Flint 

 creek just south of Phelps, Ontario co., where there lie on top 

 of the Stafford limestone about 50 feet of these shales, the cal- 



