630 CHARLES BUTTS 



Carboniferous System. The Catskill formation is about 2,000 feet 

 thick. Probably 80 per cent, of its rocks are red shale and red or 

 brown sandstone, the rest of the formation being gray or green shale 

 or sandstone. The red shale predominates. It is mainly argillaceous 

 and is bright red in outcrop; the red sandstone generally weathers 

 to a gray or dull brown color, and shows its true color only on a 

 newly broken surface. The sandstone is medium- to fine-grained, 

 and may be thick- or thin-bedded or even laminated. It generally 

 occurs in thin layers or strata interbedded with shale, but may occur 

 in thick-bedded strata having a thickness of 50 feet. No fossils were 

 found in the formation, and their absence as well as the red colora- 

 tion sharply distinguishes it from the Chemung. Fig. 9 is a photo- 

 graph showing the contact of the Catskill red shale with the overlying 

 Pocono sandstone at the curve about i mile south of Kittanning 

 Point, where the Pennsylvania Railroad turns westward into the 

 gorge of Sugar Run. (See Fig. 3.) 



