Page:Report on the geology of the four counties, Union, Snyder, Mifflin and Juniata (IA reportongeologyo00dinv).pdf/183

Rh lime shales, which are spread over a wide area in this township on both sides of the Shade mountain or Selinsgrove anticlinal.

The drainage is all southward and eastward into the river through Penns creek and Middle creek, each of which drains an equal portion of the township through smaller tributaries.

The Shade mountain (or Selinsgrove) anticlinal axis is the most important structural feature in the township, crossing Middle creek a short distance below Kantz’s mill, with the top of the lower Clinton shales on its crest; and passing eastward through Selinsgrove and sinking rapidly in that direction to carry down the ore sandstone, the lower Salina red shales and the upper Salina marls in approaching the river. From this central line all the rocks dip north and south towards the Northumberland and Shamokin synclinal basins respectively.

The rock series therefore extends from a little below the Ore sandstone measures of No. V upwards to a thin band of the Catskill No. IX, exposed in one or two places along the south flank of Middle branch near the Jackson township line.

At Middle creek the Selinsgrove anticlinal is slightly furrowed by the presence of a synclinal dimple along its crest, well seen in the outcrop of the Ore sandstone and the Bloomsburg red shales. The arch of the axis is very flat, showing dips of from 10°–15° each way.

The Bloomsburg red shales or lower Salina rocks enter from Middle Creek township on the north side of the anticlinal a short distance above Kantz’s mill, and create a broad band outcropping eastward to the brick school-house, where they are exposed well on a 15°–20° dip, conforming to that of the dying anticlinal, and making a low ridge in front or north of that made by the Ore sandstone, Just south of the school-house the dip is N. N. E. and about 80′ of the Bloomsburg red shale is exposed there, gradually blending southward into the Clinton olive lime shales, which weather brown and are quite massive and laminated. The dip decreases in these shales to about 10°, immediately overlying