DESCRIPTION OF THE FORMATIONS. F 2 . l'.\ 



shales of the Chemung are succeeded by yellow shales which 

 also serve as a distinguishing mark. 



At a short distance above this level the Catskill type is 

 distinctly marked, palseontologically, by the occurrence of 

 its characteristic first remains. In the southern basin these 

 are found on four distinct horizons, the lowest of which is 

 within 100 feet of what has been assumed as the summit of 

 the Chemung. They consist of scales of Bothriolepis and 

 Hoi opt i i chilis, the former being specially abundant. In 

 the northern syncline few traces of these fossils have been 

 found, but these traces are as nearly as possible upon the 

 same level. The inference is therefore warranted that the 

 top of the Chemung lies, both on stratigraphic and palse- 

 ontologic evidence, at or near the dividing plane between 

 the olive shale and the red sandstone. 



The beds overlying the Chemung group in Perry county 

 are unusually interesting, having afforded a large number of 

 fossil remains. 



The fish beds. 



The first of the beds in question is the lowest fish bed, 

 which being double may be considered twx> beds. It is a 

 complete mass of scales, for the most part broken, and from 

 the crumbling nature of the stone very difficult to extract. 



Above this, with an interval of about 200 feet, is a thin 

 bed (4 inches) of green shale filled with casts of Spirifera 

 mesostr talis, a Chemung species. 



The King s Mill sandstone. 



More than two hundred feet higher still comes the most 

 remarkable bed in the wiiole series, which I have called the 

 King's Mill sandstone, from its specially clear exj3osure near 

 King's Mill, two miles northwest of Duncannon. It is here 

 exposed in the fields of Mr. G-. Brunner (and by the roadside 

 at Linton's hill a mile to the west) as a bed of white sand- 

 stone, some lenticular layers of which are merely masses of 

 stone honeycombed by the cavities left by the solution of 

 the shells of Schizodn^ rhombeus, Hall, and others, mostly 

 Lamellibranchiates. These fossils occur only in places. If 



