Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/63

Rh It seems to rapidly expire westward towards Granville as a distinct roll, unless indeed it be associated with the Chestnut ridge axis, which from the neighborhood of Lockport southwest to Matawan, opposite McVeytown, has elevated the Ore sandstone above the surface in a double ridge, carrying on its flank a double outcrop of the overlying “Sand Vein” ore bed for a distance of about 7 miles. It is quite probable, however, that this is a distinct flexure.

9. The Blue Ridge-Slenderdale anticlinal, the next south, gets its strength and importance from the western side of the district—the reverse to the East Shade mountain. It is not nearly so strong an axis either, for it has only managed to push apart the Medina sandstone wall, making an interior elevated plateau of the red Medina sandstone and shale between the two opposing walls—Blue Ridge and Licking Creek mountains—both of which when coming together take the former name where the subsidence of the anticlinal has closed up the break and united the ridges.

This axis steadily increases in strength from the Huntingdon county line to Minehart’s gap and with opposing dips of from 40° to 55°. East of the gap it subsides gradually to the Juniata at Grahamville, one small knob of the white Medina sandstone, IVc, being left on the east side of the river to more closely mark the course of the axis. A mile further east it carries the Ore sandstone down on its crest, with dips of 60° north and south, and for a space of 3 miles, through the valley of Horning’s run, that sandstone and its fossil ore-bed are beneath water level.

The axis however reappears with increased strength in Slenderdale ridge, making a double ore outcrop at its western end, crossing Lost creek north of MeAllisterville and Cocalamus creek a mile north of the village of that name, east of which the axis steadily subsides, first carrying down the fossil ore-bed about 2 miles from the Snyder county line, and there coalescing with the small roll already described in Snyder county, north of Richfield.

10. A narrow and tightly compressed synclinal trough exists between the East Shade mountain and the Blue Ridge, marked by the channel of the Juniata river for 6