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NEW YORK STATE MUSEUM 



Brayman shales, and the want of transitional beds between the 

 clay shale and the lime sandrock (Cobleskill) suggests that there 

 is a short time interval unrepresented. This fact, together with 

 the distinctive character and local development of these shales, 

 demands their description under a separate name, as a local mem- 

 ber of the Salina series of deposits, whose exact equivalent in 

 the complete Salina series of Central New York is doubtful. 



The main mass of the Brayman shale is an olive or grayish clay 

 rock often alternating with bluish beds and weathering to a 

 lighter color, and having the appearance of a solid mudbank. Con- 

 cretions of iron pyrites are very abundant and of all sizes, though 

 generally not much larger than a man's fist. The pyrite is com- 

 monly an aggregate of crystals, often of considerable size, the 

 cube and pyritohedron being about equally represented. Exposed 

 portions rapidly oxidize changing to an ochery color, and com- 

 monly stain the adjoining shales. As already noted, no fossils 

 have yet been found in this formation. 



The best exposure of these shales is in the ravine of the shorter 

 of the two streams which join the Cobleskill between Central 

 Bridge and Howes Cave. Here, at the foot of a fall formed by the 

 Cobleskill limestone, about 20 feet of the shales are well exposed. 

 The constant play of the water over these shales keeps the ex- 

 posure fresh and the true color of the shales unaltered. The 

 pyrite nodules too are mostly fresh, oxidation affecting the surface 

 of some, while others remain perfectly bright. 



The most complete exposure of these shales is along the west 

 bank of the Cobleskill between Braymanville and Howes Cave. 

 Aboul half way between the two stations on the road which skirts 

 the river bank, occurs a good exposure. A short distance north of 

 Braymanville, a strong stream of water issues as a spring from 

 a cavity at the base of the Cobleskill. This stream supplies a 

 watering trough by the roadside and is strong at nearly all seasons 

 of the year. This illustrates a very characteristic feature of these 

 shales, namely their imperviousness, which cause springs to issue 

 all along (he line of outcrop of these strata. Below the cement 

 kilns ;il Howes Cave is an exposure of over 30 feet of these shales 



