DESCRIPTION OF THE FORMATIONS. F 3 . 63 



It is often fossiliferous, but the fossils, or rather the casts, 

 are indistinct and fragile. 



In the northwest part of the county it is very ferrugi- 

 nous sometimes simulating a poor iron ore, but in no part 

 of the county does it yield anything of commercial im- 

 portance except an inferior stone for rough walls. Neither 

 glass-sand nor iron-ore has been found in it. 



Its pulpit rocks often afford picturesque scenery, especi- 

 ally near Bloomiield. 



In those parts of the county where the Lower Helderberg 

 limestones are specially folded the Oriskany sandstone is 

 usually included in the fold, occasionally inclosing the Mar- 

 cellus ore and shales ; but as often these have been nipped 

 out and the sandstone alone remains. 



The extension of so thin a sandstone over so wide an area 

 makes the question of the mode of its formation both dif- 

 ficult and interesting. No local cause can explain its 

 origin. The most probable opinion seems to be that it in- 

 dicates an age when from some cause, perhaps subsidence 

 elsewhere, the flat bottom of the palaeozoic ocean was laid 

 dry, and the waves sorted and sifted the accumulated ma- 

 terial, washing away the finer and lighter j:>ortion and accu- 

 mulating the coarser and heavier on banks and shoals and 

 spits, distributed according to the direction of the winds 

 and currents, but with tolerable uniformity. The adoption 

 of this opinion, it must be remembered, implies the admis- 

 sion of great destruction of preexisting deposits in order to 

 form so vast sand beds, for the shales underlying the Oris- 

 kany, though flinty in Perry county, do not usually afford 

 much siliceous material. This view is beset with fewer dif- 

 ficulties than any one which involves the introduction of rhe 

 sand from outside the Oriskany area and its even distribu- 

 tion. 



The absence also, now certain, of the next overlying 

 group, the Upper Helderberg or Corniferous, strongly con- 

 firms the belief that Perry county and the adjoining part 

 of Middle Pennsylvania was dry land or shallow water dur- 

 ing this interval. To some extent then the Oriskany sand- 

 stone of Perry county may be coeval with the Corniferous 



