Claypole.] ^68 [April 6, 



geology of Perry county and of Middle Pennsylvania. In itself in nowise 

 remarkable, it abounds in organic remains whicli when worked out will 

 yield a rich fauna. 



It is at present impossible to decide the exact horizon to which this sand- 

 stone belongs. For this reason, and to avoid prejudging the question, I 

 have retained the term "Ponent." The transcendental nomenclature of 

 Rogers is doomed to deserved extinction, but until we can determine 

 finally what terms shall take the vacant places, it is wise to retain such of 

 them as are necessary or convenient. 



There is no question regarding the extent or signification of the term 

 "Ponent" as employed by Professor Rogers. It is purely a lithological 

 term, and is neither based on nor supported by palseontological evidence. 

 In many parts of Middle Pennsylvania the dividing line which limits this 

 Ponent Group is almost as easily seen in the rocks as on a geological dia- 

 gram. 



By the term "Ponent," Professor Rogers intended to designate all that 

 great mass of red sandstone and shale, which intervenes between the top 

 of his olive " Vei'gent" shales (Chemung of New York), and the Great 

 Lower Carboniferous sandstone above them. The color and material of 

 the beds are the sole foundations on which the distinction is based. 



Palseontological considerations were not in the least regarded, partly be- 

 cause the time and means at the command of the First Survey forbade any 

 extensive search for fossils, and partly because the great barrenness of 

 these red shales and sandstones discouraged the same. 



In New York, on the other hand, though fossils were also very scarce, 

 yet an attempt was made by Professor Hall to establish a palseontological 

 basis for his " Catskill Group," and the few relics that were obtained from 

 the scanty exposures of these red shales and sandstones in that State 

 were considered "characteristic." These are, strictly speaking, only two 

 in number — HoloptycMm Americanus and Sauripteris Taylori. 



The base of the Catskill Group in New York is therefore double, litho- 

 logical and palseontological. It may be to some extent an open question, 

 whether or not these two horizons exactly coincide, and possibly the ques- 

 tion may not admit of solution from the few and obscure exposures in that 

 State. But until the coincidence of the horizons in New York with those 

 in Pennsylvania is definitely settled, it would be premature to assume it. 

 Consequently I retain for the present the term "Ponent" in writing of 

 these beds. 



The Kingsmill white sandstone lies near the base of these red sandstones 

 and shales. Consequently it is in the Ponent Group of Pennsylvania, Its 

 exact position is about 600 feet above the actual base of the red shales and 

 sandstones. Palseontologically, the evidence leads to the same conclusion 

 for about 400 feet below it are two fish-beds full of the remains of Saurip- 

 teris and Roloptychius. There is consequently no question of its position, 

 judging from the data that have been hitherto accepted by geologists. 

 Whether or not turther examination of the Kingsmill sandstone will compel 



