416 A. W. GRABAU — PALEOZOIC DELTA DEPOSITS OF NORTH AMERICA 



continuation of Bald Eagle Ridge, it is only 100 feet thick and repre- 

 sented by a gray sandstone. Rogers and Jackson 23 suspect there may be 

 some reduction by faulting here, but even if so this can not be very much. 

 Elsewhere in Bedford County, south of Morrisons Cove, the Bald Eagle 

 is not recognizable. In the westward section this is partly due to the 

 fact that the plunge of the folds carries it below erosion level, and we are 

 thus unable to trace its southwestern extent. Thus where Wills Creek 

 cuts through Wills Mountain in Allegany County, Maryland, the lowest 

 formation shown is the Juniata, the Bald Eagle not appearing. Xever- 

 theless, there is every reason for believing that the formation soon dies 

 out in this direction. 



Its occurrence in other gaps is well described in Lesley's summary 24 as 

 follows : "Gray sandstones . . . appear in Ravers Creek Gap through 

 Tussey [Mountain], on the Henrietta road in AYoodberry township, and 

 obscurely at two places on Bunnings Mountain; but Oneida [Bald 

 Eagle] beds are certainly absent along the RaystoAvn Juniata, in both 

 Tussey and Evitts Mountain gaps. In fact Oneida [Bald Eagle] sand- 

 stone beds were seen by him [ Stevenson] at no locality in Bedford County 

 more than 35 inches thick. At the two places last mentioned there can 

 be no question of concealment by faults, for the top layers of number 3 

 [Hudson River beds] are regularly overlaid by Medina [Juniata] red or 

 brownish red shales, containing two fossils which unmistakably belong to 

 that division (A nib onychia [Byssonychia] radiata and Rhynchonella 

 capax [perhaps Ortliorliyneliula linneyi}), and the Hudson River slates 

 pass without any break of sequence upward into Medina [Juniata] 

 slates." Xortheastward in Tussey Mountain the Bald Eagle and Juniata 

 are not shown, the Tuscarora forming the base- of the mountain, and 

 resting here by overthrust on the Hudson beds, cutting out locally the 

 lower sandstones and red beds. In Logans Gap, however, through Jacks 

 Mountain, almost due east of T}'rone Gap, the Bald Eagle is well 

 developed, resting on about 2,300 feet of Martinsburg shales. The 

 basal member is 310 feet thick and consists of hard, greenish gray sand- 

 stone, mixed with pebbles of quartz smaller than those in the upper part, 

 and hard, fine-grained sandstone, witli small scattered pebbles and much 

 disseminated iron oxide. The upper division consists of massive sand- 

 stones, reddish in color, full of small pebbles, which in some places be- 

 come as large as hen's eggs. It also has a thickness of 310 feet, giving a 

 total of 620 feet for the series. It is significant that these beds are much 

 coarser than those farther west, showing a closer approach to the source 



23 Geology of Pennsylvania, vol. i. p. 128. 



24 J. P. Lesley : Summary, First Report Geology of Pennsylvania, vol. I, pp, 663-665, 



