' DEVONIAN AND CARBONIFEROUS FORMATIONS. 177 



Clinch (^Meclina-Oneida) Sandstone. — A coarse white or slightl}^ mot- 

 tled sandstone, varying in thickness in this portion of the valley from 

 100 to 250 feet. It is the most conspicuous member, as it is the chief 

 ridge-making formation, and much of the surface is covered with its 

 debris. In this immediate region it differs slightly from its general 

 aspect, for here it carries imbedded between its massive layers at least 

 one bed of soft red shale about six or eight feet in thickness. Its total 

 thickness is probably the minimum as given above, but that is some- 

 what uncertain, as it is faulted where measured and so affords no positive 

 evidence. 



Rockwood (Clinton) Formation. — This formation consists almost en- 

 tirely of shales, some of which are non-fissile and highly fossiliferous, 

 containing crinoid stems in abundance. Its thickness was undetermined, 

 and the formation is of no consequence, except that by its fossils the age 

 of the sandstone forming Draper mountain was positively determined. 



Giles (Lower Helderberg-Oriskany ) Formation. — Lying above the Rock- 

 wood shales, on the south side of Draper mountain, is a formation ex- 

 ceedingly difficult to classify, as its exposures are rare and unsatisfactory. 

 The only rock exposed is a blue, crystalline limestone, the probable 

 equivalent of the Helderberg, and it is not known whether there are any 

 sediments properly belonging to the Oriskany or not ; there is apparently 

 room for them, Ijut nothing shows. 



Devonian : Walker black Shale. — This constitutes the lower portion of 

 the great series of Devonian shales and is separated entirely by its color. 

 It is a black, carbonaceous shale, and the passage from this into the 

 green shale above is very gradual and is accomplished by interbedding, 

 so that it is impossible to determine exactly where the line should be 

 drawn. It is arbitrary at best, and serves only to show that the base is 

 essentially a black shale which, in a broad way, is clearly distinguishable 

 from the green shale above. 



Kimberling Shale. — This division includes all of the shales above the 

 Walker and beneath the Carboniferous sandstone. Its base is the transi- 

 tion series, already described ; these pass upward into green, argillaceous 

 shales, which grow more sandy as we ascend, until in the upper portion 

 it carries many thinly bedded sandstones and some conglomerates. 



Carboniferous: Price (Pocono) Sandstone. — Above the Devonian sedi- 

 ments, but separated by no distinct line, is the important coal-bearing 

 formation of this region ; it consists of an alternating series of coarse 

 yellow or green sandstones, beds of shale and coal. In character these 

 sediments resemble closely those of the Upper Coal Measures in the 

 Appalachian basin to the northwest, but it is a significant fact that the 

 deposits of coal thin out rapidly to the northwest, across the strike, as 



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