70 P. REPORT OF PROGRESS. E. W. OLAYPOLE. 



parently new. Localities will be found mentioned in the 

 reports on the townships. The thickness does not exceed 

 about 200 feet. 



No. Vlllf. Chemung group. 



The rocks of this age occupy a large area in the county 

 along three separate outcrops. 



The most northerly of these is a curve coming out and 

 running round the west end of the Buffalo syncline. Its 

 extreme length is about 44 miles. 



The second or southern outcrop of the Chemung shales 

 is a similar curve running round the west end of the Cove 

 sycline. The total length of this curve is about 26 miles. 



Between these two outcrops is another of less extent, a 

 long narrow monoclinal strip skirting the south slope of 

 Mahanoy ridge. It is originally the northern part of a third 

 syncline which lay between Mahanoy ridge and Dick's hill, 

 the southern portion of which has been cut off by the Perry 

 county fault. Eastwardly also this Chemung outcrop is 

 limited by the duplication of the Hamilton rocks at the 

 end of Mahanoy ridge, which forms the continuation on 

 another line of the Perry county fault and the third sum- 

 mit of Half Falls mountain. The details of this continua- 

 tion and repetition of the fault will be found in the report 

 on Watts township. 



The Chemung group in this county consists entirely of 

 olive shales and fine-grained, thin-bedded sandstones. They 

 may be distinguished after a little practice from the Gen- 

 essee and Portage shales below them by their lighter color. 

 Upwardly they change gradually in most places into the 

 ( 'a I skill red shales by becoming more and more stained with 

 iron This change is specially noticeable in the northwest 

 where the Upper Chemung shows a much closer approach 

 both in color and fossils to the corresponding beds in the 

 northern part of the State. See report on Saville town- 

 ship. 



Tin' group is well characterized by its fossils, though these 

 air rarely found in good preservation, the contortion and 

 pressure to which the rocks have been subjected having 



