370 F a . REPORT OF PROGRESS. E. W. CLAYPOLK. 



mation makes the southern barrier of the township as de- 

 scribed above. 



Green valley and Kennedy's valley are troughs of Clin- 

 ton and Onondaga No. V in folds of this outcrop. 



There is no gap in the outcrop of No. IV from end to end, 

 but a road into Cumberland county crosses the mountain 

 by a notch in the crest called McClnre' s gap, at the back 

 of Welsh hill, where the Medina sandstone is cleft over the 

 anticline. 



The dip of the Medina rocks is everywhere so nearly ver- 

 tical that the breadth of the outcrop nearly measures the 

 thickness of the formation. It contains no minerals of 

 value. 



The Clinton group, ( V.) 



Two outcrops of the rocks of this group cross the town- 

 ship. 



One extends along the whole line of the Blue mountains 

 from the Spring township line, round Green valley, to Welsh 

 hill ; along both sides of Kennedy's valley ; and along the 

 north side of Mount Dempsey, passing out of the township 

 into Shaeffer's valley. 



The other saddles the end of Bower mountain. 



The former of these outcrops has a length of about 18 

 miles, chiefly through a wooded country. High up on the 

 Blue mountains runs the outcrop of the Iron sandstone 

 supporting the lower green shales. 



The Iron sandstone is somewhat thicker in this part of 

 the county than in the north, and makes a visible terrace 

 round the prominent points of the mountain. The terrace, 

 however, is largely due to the Ore sandstone. 



An excellent example of the relation of these beds may 

 be seen in Pilot Knob. Viewed from any of t lie limestone 

 ridges near Landisburg the central mass of the Medina sand- 

 si one is seen composing the highest knob, behind which in 

 Cumberland county lies Doubling hollow. 



In front of and surrounding it like a wall is a lower ridge 

 formed by the Clinton outcrop, with its two sandstones. 

 Between this lower ridge and the main mountain a trench 



