Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/64

36 F³. miles through the “Narrows,” but scarcely discernible for any distance on either side of the river. It carries only the lower Clinton measures, which have been largely eroded from the flank of both mountains through the gap.

ll. The Licking creek synclinal, lying south of the Blue Ridge, is a long narrow trough watered by Licking creek, and occupied largely by the lower Clinton rocks in Mifflin and part of Juniata county.

Approaching the river however, the basin deepens and widens out, receiving the Ore sandstone at about 8 miles from the Juniata in Mifflin township, and a thin strip of the upper Salina marls, with some Lower Helderberg (?) limestone about 4 miles long, which closely marks the axial line. East of the river it is not so well defined, passing through Fermanagh township a little north of Lost creek, and into Fayette a little north of Oakland Mills.

East of McAllisterville it takes new importance by deepening to include the lower Helderberg No. VI and Oriskany sandstone (chert) No. VII; but it soon flattens and dies out east in lower Devonian measures which occupy so large a part of the four eastern townships of Juniata.

12. The East Shade mountain anticlinal must also be taken up at the Huntingdon county line, where it is most conspicuous and has produced the greatest effect. Under the name of the Black Log mountain anticlinal in Huntington county it traverses lengthwise that beautiful valley for nearly 18 miles, with the Black Log mountain on the north and Shade mountain on the south, itself a fertile floor of limestone No. II and slate No. III.

This description answers in Juniata county, although the axis has already begun to subside, carrying down the limestone first in 3 miles, then the slate in 10 miles, and finally brings together successively the three divisions of the mountain rock No. IV, until the uppermost of these, the white Medina IVc, sinks beneath the Clinton measures in Milford township, about 4 miles from the river. It is only on the