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NEW YORK STATE MUSEUM 



The best exposure of this rock is on the road along the left bank 

 of the Cobleskill and a short distance west of Howes Cave [pi. 

 4]. Here the rock is seen capping the Brayman shales, with a 

 thickness of about six feet, and is in turn succeeded by the 

 cement beds of the Rondout. As before stated the line of contact 

 between the Brayman shale and the Cobleskill is marked by a 

 somewhat conglomeratic layer, indicating a certain amount of 

 wave activity. The Cobleskill itself is a normal lime sand- 

 rock, more or less crinoidal, and showing a certain amount of 

 crystalline character. The main portion of the rock consists of 

 fragments of shells and crinoid joints, Avith masses of coral 

 scattered through them, these latter not uncommonly overturned. 

 From below the limestone, springs issue at several points, some 

 of them forming deposits of calcareous tufa over the underlying 

 shales. 



Another good locality for seeing the contact of the Brayman 

 shales and the Cobleskill is at the old pyrite mine, a short distance 

 south of the Gebhard bridge across the Schoharie [map : IX 1, 15]. 

 The Cobleskill is seen capping the Brayman shales, and shows here 

 a marked jointing, which causes the rock to split into long and 

 narrow blocks, the width of which is often much less than the thick- 

 ness [pi. 6]. Several exposures of the Cobleskill are seen in the 

 face of Dann's hill and West hill north of this point, one easily 

 accessible being at the mouth of Clark's cave, or Gebhard's cave as 

 it is commonly called [see p. 251]. The Cobleskill is well exposed 

 at the head of the shorter of two streams between Howes Cave 

 and Central Bridge [map : VII h, 19] Avhere it causes a fall, owing 

 to the undermining of the Brayman shale. Large fallen blocks 

 here show the massive character of the bed. In the hillsides of 

 I his vicinity the bed crops out and again northward from here on 

 I lie road to Grovenor Corners above Central Bridge. The bed is 

 again seen in the hillside east of Schoharie. It appears first on 

 both sides of the street leading east from Schoharie postoffice ; on 

 the south of the road it crops out in ledges while just north of the 

 read it was formerly quarried in the old Brown quarry [for sec- 



