CHAPTER IV.
Detailed Geology of Union County.
1.Gregg Township.
This is the most northern township of Union county, lying on the west bank of the Susquehanna river, north of White Deer mountain and embracing about 15 square miles.
All the drainage is eastward into the Susquehanna River. Black run on the north and White Deer Hole creek, with its branches, Spring creek and South creek, in the center, are the two principal streams.
Alvira P. O. is a small village located upon the Lewistown or Lower Helderberg limestone in the northwestern part of the township near the Lycoming county line. Uniontown, or Allenwood P. O., the chief village of the township, is situated upon White Deer Hole creek, not far above its entrance into the river, and close to the Philadelphia and Reading R. R.
The geological rock series extend upwards from the Medina white sandstone, making the crest of the White Deer mountain anticlinal along the south border line of the township, to the Marcellus and Hamilton measures No. VIII, in the valley of Black run along the northern border.
All the measures dip N. N. W. except in a small synclinal roll of Lower Helderberg limestone and Oriskany sandstone extending for about a mile west of the Uniontown-Alvira road from the Presbyterian church.
The Medina sandstone of White Deer mountain is nowhere exposed in place; but the rocks of this formation extend along the southern township line for about 3 miles before sinking under the Clinton measures which continue the ridge and axis for 2 miles further to the Susquehanna river.
