Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/125

Rh in this township before subsiding beneath the lower Clinton shales and sandstones. which extend the ridge to and beyond Spruce run into White Deer township.

A compressed synclinal extends along the south base of the Buffalo mountain, carrying for a mile west of Spruce run a narrow tongue of the Bloomsburg red shales, separated from the mountain by a low ridge of the Ore sandstone.

In the valley of Black run, the Jones mountain axis carries on its dimpled crest the Clinton rocks in a belt a mile wide, with dips of only about 10° along the axial line, stiffening to 40° or 45° to the north and south.

Armstrong run waters a synclinal valley of upper Salina rocks flanked north and south by low ridges of Bloomsburg red shale. The latter rocks between Armstrong and Rapid runs lap over the dying end of the Little Buffalo mountain anticlinal, which become much more prominent to the west in Center county, where it forms the southern sub-division of the Penns Valley axis, running through the Penns Valley Narrows. This axis expires about a mile and a half east of the Buffalo—West Buffalo township line, carrying the upper Clinton and lower Salina rocks on its crest and if continued passing through Mazeppa.

Rapid run, on the south side of this ridge and axis, waters a synclinal valley of upper Salina rocks, similar to, but not quite so wide as that of Armstrong run; and these two synclinals, separated by the Little Buffalo mountain anticlinal, form together when continued eastward, the great Lewisburg or Lackawanna synclinal.

The Paddy Mountain anticlinal, lying south of the Rapid run basin, likewise expires in Buffalo township along the south base of the Limestone Ridge. Its crest as it sinks beneath the wide plain of upper Salina rocks is dimpled along the West Buffalo township line, showing two anticlinal prongs of the Bloomsburg red shales, separated by a narrow tongue of the upper Salina rocks. These latter shales and limestones are considerably twisted and curved further east by the effect of this axis, and in all the territory, both north and south of the Lewistown and