38 J.J. STEVENSON — LOWER CARBONIFEROUS, APPALACHIAN BASIN 



the lower or larger portion is an olive mud rock, while the upper, also 

 olive colored, is very largely a fine grained sandstone, many layers of 

 which are excellent for building purposes, while others have been used 

 for grindstones. The upper portion is characterized by a Spirophyton 

 resembling that of the New York Cauda-galli grit.^ The upper or sandy 

 portion is the protecting cover of the "knobs" of eastern Kentucky. 

 Professor Crandall's notes on Greenup and Rowan counties confirm Mr 

 Lesley's statement, for he describes the Waverh^ as upward of 500 feet 

 thick, consisting of fine grained sandstones and shales, with la3^ers of 

 good building stone at the bottom and at other horizons. This accords 

 with Professor Andrews's description of the formation as it exists in 

 southern Ohio and the adjacent portion of Kentucky. The Kentuck}- 

 geologists did not think that the Ohio subdivisions can be recognized 

 in their state. Professor Herrick's work, however, has removed much 

 of the difficulty. 



In Kentucky the mass grows more and more sandy northward, and 

 all trace of limestone seems to be wanting near the Ohio river. It is 

 evident that on this westerly side of the basin the conditions are like 

 those described on the easterly side, and that the change from merely 

 land detritus to calcareous rock begins in middle Kentucky as at the 

 east it begins in southern Virginia, with little difference in the latitude. 



GEOLOGICAL RELATIONS OF THE POCONO 



We have followed the variations of the Pocono around the Appalachian 

 basin and, by means of the oil-well records, under much of the interior, 

 where the formation lies deeply buried. The characters are distinct 

 throughout except in the northern outcrops of eastern Tennessee, where 

 for 100 miles detailed information is wanting, thoug"!! on both sides of 

 that space the conditions are clear, the features at the south being those 

 foreshadowed by the changing structure and composition in southwest 

 Virginia. 



We have seen that the great mass, as observed in Pennsylvania, retains 

 its general characteristics and thickness into Virginia, in which state its 

 upper portion becomes less coarse and more shaly until within 60 or 70 

 miles of the Tennessee border, where calcareous dei)osits appear, and the 

 formation becomes closely related to the overlying limestone mass, while 

 the lower portion, which has retained its detrital character, seems to be 

 merged into the Upper Devonian, the Grainger shales of M. R. Camp- 

 bell. The change continues southward in the upper portion, and the 

 deposit becomes mixed calcareous and silicious, often chert. Along the 



* Joseph Lesley : Fourth report on the geology of Kentucky, 1861, pp. 451, 452. 



