Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/416

388 F³. what calcareous, first shows in the bed of the creek on a 40° N. W. dip succeeded by exposures on both sides of the cross roads, above and below Beale’s S. M., of grey slates and sandstone, the latter breaking in blocks, but the former largely predominating, on dips of 35° and 30° N. 25° W.

The Marcellus black slates and limestone are wanting. The Hamilton measures show near the forks of the creek at J. Grey’s on a 20° N. W. dip and underlie an upper Hamilton shale and Chemung ridge which rises with well rounded summits to the north of this point, right in the center of the Tuscarora synclinal.

On the north flank of this ridge going towards Peru, reddish-brown sandstone shows near Reeder’s lane, dipping S. E. 25°.

A short distance east of the Cross Keys store and church, along the read to Peru mills, a small outcrop of the Marcellus limestone shows in the road cut, with the Oriskany sandstone and Lewistown limestone underlying it in the hill to the north. This Marcellus limestone has a greenish cast and weathers into a very dark soil. It breaks into long narrow blocks and occurs in thin hard ribs. The dip was obscure, but evidently stiffly southeast.

In the gap of the ridge, just east of here, the outcrop of No. VI limestone is considerably increased by a small anticlinal flexure, showing dips of 20° N. W. and 50° S. E., the latter decreasing in the Oriskany sandstone.

A small quarry here has been mainly opened in the upper slaty members of No. VI, the massive limestone member being just at water level on the crest of the anticlinal, but outcropping again further up the ravine on its regular southeast dip where it could be much more advantageously opened.

At Peru Mills the anticlinal has worked into the Oriskany sandstone, which is here quite massive and apparently fully 50′ thick. Northwest dips of 40° and southeast dips of 20° were seen in sandstone at this point, and at the top of the formation there occurs a small layer of pebbly sand rock about 3′ thick, to which Mr. Dewees, in Report F, has as-