DESCRIPTION OF THE FORMATIONS. F 2 . 53 



to 1000 feet. Its thickness in Perry county is about 1500 

 feet. 



Onondago red and variegated sliales. 



A very close agreement may be observed between these 

 beds in the two States. In both they consist at base of a 

 thick mass of red shale overlain by another of varying col- 

 or. Indeed the descriptions given of these lower beds in 

 New York might be copied literally and applied to the Penn- 

 sylvanian rocks. 



Yanuxem says (Rep. on 3d District, p. 96) of the red 

 shale : "The great mass is of a blood-red color, fine-grained, 

 earthy in fracture, breaking or crumbling into irregular 

 fragments." And of the variegated shale he says (p. 97) : 

 "It consists of shales and calcareous slate of a light green 

 and drab color, intermixing and alternating with the red 

 shale at its lower part." Thus we have at the top of the 

 series, green, then red under it, green, red, bluish-green and 

 yellow, this latter by exposure to the air ; then green and 

 red layers with a little white and greenish sandstone, being 

 several repetitions of the first two, and finally red shale as 

 the lowest visible mass. 



No better description can be given of these two groups 

 as they occur in Perry county. 



The thickness of the separate beds is not mentioned in 

 the Report of the New York Survey, but in Perry county 

 they form two masses of about 700 feet each, giving to the 

 whole group, as usual, a thickness considerably greater than 

 that which it has in New York. 



Again (p. 97) : "In several localities the red shale shows 

 numerous green spots, varying from an inch or two to sev- 

 eral inches in diameter." "The red shale presents a thick- 

 ness of from one to nearly iive hundred feet, yet nowhere 

 has a fossil been discovered in it, or a pebble, or anything 

 extraneous excepting a few thin layers of sandstone." 



Similar green spots occur in the Red shale in Perry 

 county, as near ^Yaggoner's mills and other places. The 

 great scarcity of fossils is also remarkable, though they are 

 not totally absent in Pennsylvania, as will be seen below. 



