Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/405

Rh the north the Black Log valley, or Shade mountain axis, carries a triangular area of No. III slate on its crest for about 2 miles east of the Lack township line, beyond which the valley is enclosed by a single high ridge of Oneida sandstone extending 1½ miles beyond the slate and enclosed, in its turn, by the red Medina No. IVb rocks which create an elevated plateau within a double ridge of the Medina IVc sandstone bounded north by a small triangular wedge of the Clinton rocks in the Licking Creek valley.

The Academia anticlinal extends for nearly 4 miles into this township from Beale and is well marked for that distance carrying a double outcrop of the Ore sandstone on either flank to within a couple of hundred yards of the Reed’s Gap road.

Its subsidence at this point brings the Medina sandstone of Shade mountain and the Oriskany sandstone of the North Limestone ridge within 1½ miles of each other along the Lack township line, while the same rock and ridges are 3 miles apart along the Beale township line. An elevated and gentle synclinal basin occupies the territory between the Shade mountain and Academia anticlinal, flanked on either side by the Ore sandstone ridges and filled up with the Salina measures. This is a virtual continuation of the Mifflintown synclinal and cannot be detected at Reed’s Gap.

The main Tuscarora synclinal enters the township in the high Hamilton ridge just south of Tuscarora creek, crossing the road leading south from McCoysville on the south side of the creek with south and north dips of 25° and 10° respectively. From here it may be traced directly west through the high ridge to the Presbyterian church at McCollough’s S. M. ; and from that point it continues south of Willow Run to the Lack township line.

On the south side of the township the outcrop of the Oriskany sandstone and Lewistown limestone is interrupted just north of Bealetown by a small fold over the western end of the small anticlinal which has already been traced through Turbett and Spruce Hill townships, and which expires upon reaching Tuscarora creek, a mile west of Bealetown.