L62 F\ REPORT OF PROGBE88. E. W. CLAYPOLE. 



spicuous outcrop and present no features of importance. 

 All are probably present in full thickness, and by their 

 disintegration contribute to the formation of the valley 

 called Sandy Hollow. 



The Hamilton sandstone. 



The Hamilton sandstone shows two outcrops in this town- 

 ship, one of which forms a long straight line from E. N. E. 

 to W. S. W. from the road between New Bloom field and Del- 

 ville to the township line near Falling Spring. This ridge 

 is the real continuation of Dick's hill, with a trend rather 

 more to the southward owing to the intrusion of the tongue 

 of red shale, &c, that runs up from Bridgeport. 



It is also a continuation in the opposite direction of Pisgah 

 hill, but these names are not usually applied to this portion 

 of the range. Common usage limits the term Dick's hill to 

 the range in Wheatfield township, and Pisgah hill to that 

 southwest of Sherman's creek, the intervening part being 

 usually known as the Rock hill from its precipitous termi- 

 nation at Gibson's rock on Sherman's creek. 



In this ridge the beds on the northern side dip very 

 sharply, but the angle becomes less and less so that on its 

 south side it seldom exceeds 30°. In consequence of this 

 increase of dip the breadth of the range much exceeds the 

 thickness of the bed of sandstone of which it is composed. 



Like the other ridges of Hamilton sandstone, this is steep 

 and covered with wood, especially on its northern side. 



The only cut in Rock hill through which water passes from 

 the north side to the south is Gibson's gap, which affords 

 one of the most beautiful examples of the erosion accom- 

 plished by a small stream that can be found in Perry county. 

 The bold peak of Pisgah hill, which here reaches its greatest 

 altitude, shows the height of the barrier through which the 

 creek was compelled to pass on its way to the sea. The steep 

 hard cliffs of sandstone which rise <>n both banks show the 

 nature of the obstacle. For nearly half a mile the stream 

 winds along between almost perpendicular walls till it 

 emerges from its confinement to wander more freely over 





