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NEW YORK STATE MUSEUM 



[fig. 147], marked by the strongly trilobed and pustulose central 

 portion of the head and a strongly spinose pygidium; Proetus 

 f o 1 1 i c e p s [fig. 148] and P. clams [fig. 149], the former 

 distinguished by its rounded cardinal angles, tumid, faintly fur- 

 rowed glabella and rounded pygidium without marginal fold; the 

 latter by long cardinal angles, glabella without lobes, and short 

 crescentic pygidium with marginal fold. 



Marcellus shale 



In all the hills bounding the Schoharie valley between Scho- 

 harie and Middleburg, with the exception of West hill, the Onon- 

 daga limestone is succeeded by about 180 feet of black, fissile 

 shales, which split up into thin leaves and become more or less 

 rusty on exposure. These are the Marcellus shales, which repre- 

 sent the mud deposits succeeding the coral reefs of the Onondaga 

 period. They are not extensively exposed in this region, for on 

 all the hillsides they have weathered so much that the out- 

 crops are covered with soil. They form the gentler slopes above 

 the limestone terrace, and are surmounted by the steeper slopes 

 of the arenaceous Hamilton beds overlying them. 



One of the few accessible localities where the Marcellus shales 

 can be examined is on the eastern base of South hill, northwest 

 of Middleburg. North of the farm of Mr Henry V. Pindar and 

 between it and a point opposite Borst Mills (at which locality 

 the lop of the Onondaga forms the river bed) several exposures 

 occur in the bottoms of small streamlets which incise the slope 

 of 1he hill. Some of the beds are exposed along the road, 

 where it descends to the flats of the river. The highest beds are 

 bcsl shown about a quarter of a mile north of Mr Pindar's 

 house, where an unsuccessful attempl has been made to mine the 

 upper, layers for coal [ma]): VIII i, 87]. This locality is best 

 approached by a path which branches from the road where this 

 has reached the level of the Hals. At the "coal mine" the shale 

 is very black and carbonaceous, the upper four feet having suf- 

 fered some crushing and internal shearing owing lo the. pressure 

 of the overlying rock and the yielding character of these car- 



