SUCCESSIVE DEPOSITS IK THE APPALACHIAN REGION 437 



part red, gray, and greenish shale. High in the mass are found stem- 

 like vegetable forms resembling an irregular Scolithus. This appears to 

 be the Scolithus verUcalis of Hall, a fossil of the Medina sandstone of 

 New York." 52 So far as these tube fillings can be taken as horizon 

 markers, they would indicate the upper beds of this series to be "Medina" 

 and not Queenston. 



In Mill Hall Gap, Clinton County, the scries is not well exposed, the 

 beds overlying the Bald Eagle conglomerate consisting of "thin-bedded 

 gray and red clay sandstones, constituting three parts of the whole mass 

 separated by and alternating with beds of red, gray, and greenish shale." 53 

 The Scolithus verticcilis has also been found in the uppermost beds. The 

 series is about 700 feet thick and is followed by an equal amount of 

 hard massive red, gray and white sandstones, the Tuscarora. 54 In Ly- 

 coming County, finally, the Juniata is reported by Franklin Piatt as 

 having a thickness of 1,200 feet, the Tuscarora being estimated at 100 

 feet, while the Bald Eagle is only 75 feet thick. 55 



Returning to the more southeasterly outcrops, we find an excellent de- 

 velopment of the series in Logan Gap, through Jack's Mountain, in 

 Mifflin Countjr, Pennsylvania. The top of the mountain is formed by 

 the great white Tuscarora sandstone, here 820 feet thick, while the 

 Juniata has a thickness of 1,280 feet. It consists of soft, friable reddish 

 sandstones and red sandy shales, the latter commonly showing ripple- 

 marks and mud cracks, while some of the sandstones show marked cross- 

 bedding, apparently of the torrential type. Ten miles southward along 

 the strike, at Orbisonia, in Rockhill Gap through Black Log Mountain, 

 the red beds are 930 feet thick and consisl of soft brown and red clay 

 sandstones and shales. 



Tn the Susquehanna Gap through Blue Mountain, above Eafrisburg, 

 true Juniata is wholly absent, the few feci of red shale underlying the 

 Tuscarora, which here forms the mountain crest, belonging to the typical 

 Medina of New York, and resting unconformably upon the Hudson beds. 



Further south, in Franklin County, Pennsylvania, the Juniata forma- 

 tion, as we have already seen, rests on the upper Martinsburg shale, which 

 passes upward by gradation into the \\^\ beds. The lower beds are dull 

 red, cross-bedded sandstones with pebbles and galls of clay shale alter- 

 nating with bright red shales. Above the lower 200 lVe( shales are less 

 common, cross-bedded reddish Bandstones predominating often with clay 

 pebbles. The thickness varies from 300 to 150 feet, (he upper 60 feel 



M Rogers, Ioc. cit, p. 120. 



M Lesley, loc. cit., pp. 659-661. 



"■'11. M. Chance: Reporl <:,. Clinton County, L880, p. 120. 



55 Report G,., p. 120. 



