362 F". REPORT OF PROGRESS. E. W. OLAYPOLE. 



Light. The structure of the valley will be understood by 

 reference to Plate XL, Fig. 1. 



The shaded parts of the diagram represents the existing 

 locks on the north and south sides of the valley. The dot- 

 ted lines above it represent part of the mass that has been 

 removed by the erosion of the strata. It will be seen that 

 formerly the sandstone covered the Cambro-Silurian beds, 

 and formed an anticlinal mountain of great height, and 

 of a shape like that of the still existing ridge in Madison 

 township. But the continued erosion cut away the top of 

 the arch until the lower beds between or under the sand- 

 stone were exposed. These lower beds consisting of softer 

 shale were then rapidly worn out and carried off by the two 

 draining streams, by Horse Valley run in Tuscarora creek 

 and by Tuscarora creek itself; further west until the present 

 valley was scooped out and its sandstone walls being harder, 

 were left forming two separate and parallel ranges instead 

 of a single range as at first. 



The Trenton limestone. No. II. 



If the Trenton limestone occurs in the valley, its exposure 

 must be small and indistinct. I could learn nothing of it 

 except that occasionally pieces of limestone had been picked 

 up near the narrows. But these may have been brought 

 from outside the valley. 



The Utica shale, No. Ill, a. 



These, the oldest rocks certainly existing in Perry county, 

 may be seen cropping out in the middle of the valley not 

 Ear from Johnston & Brothers' saw-mill. They are black 

 and break irregularly. Cleavage is rather strongly de- 

 veloped in them, and thence it is hard to determine the dip 

 except by taking advantage of some variation in the strata. 

 In this way. however, it is found to be nearly vertical. The 

 shales are too soft to be of any use for roofing slate and the 

 cleavage is not regular. 



.W;ir i he top of t lie Utica shales a small seam of imperfect 

 coal was found and followed some years ago by Mr. Job 

 Bockenberry. [ts quality was good, but its quantity insig- 





