72 F\ RKPORT OF PROGRESS. E. W. CLAYPOLE. 



low, rounded hills showing less definite direction than the 

 harder groups, and cut across in both directions by streams. 

 Occasionally the beds are hard enough to form steep slopes, 

 or even bluffs, as near Montebello Furnace and Newport, 

 but these are unusual. The smooth, evenly rounded hills 

 and slopes of Chemung shale present to the eye a pleasing 

 contrast with the rugged outlines of the Hamilton sand- 

 stone hills adjoining them. Their irregular drainage and 

 erosion are due to the want of hard beds to divert the 

 water-courses. Consequently weathering proceeds with 

 equal ease in all directions and chance alone determines 

 the contour of the surface. This chance contains three 

 chief factors — original variation of level, local softness in 

 the rock, and accidental diversion of the water-courses. 

 None of these can be predicted, and consequently the drain- 

 age of these Chemung districts follows no general law. 



No. IX. Cat skill formation. 



This easily distinguished group of rocks, so conspicuous 

 by its massive red beds, is an important factor in Perry 

 county geology. It occupies the middle areas of both syn- 

 clines, Buffalo and Cove. 



The immense thickness of the formation, about 6000', 

 combined with the moderate dip at which its beds lie, 

 gives a great breadth to its outcrop. This is increased 

 by the occurrence of numerous smaller local folds, especi- 

 ally in Wheatfield, Penn, and Watts townships. Pine sec- 

 tions of these may be seen along the bank of the Juniata 

 liver north of Duncan's Island, where the Chemung rocks 

 are included in the wrinkles. 



The upper limit of the Chemung is not always very 

 clearly defined. The Chemung rocks gradually assume a 

 red color, and the peculiar, thin, fine-grained sandstones 

 which characterize them disappear. But in most places 

 there is no great difficulty in limiting the bottom of the Cats- 

 kill. Occasional red beds occur near the top of the Che- 

 mung, but the division, for the purposes of this report, has 

 hem drawn where the great mass of red sandstone and shale 

 begins to appear. About this horizon also the olive-gray 



