Grant City Falls
Muddy Creek Falls
Slippery Rock Creek Gorge
REMARKS: The retreat of the glacial ice from the western end of large glacial lakes opened many outlets to the south; Muddy Creek pass was one of these outlets. Water rushed through the pass, eroding the land and deepening the gorge at McConnells Mill. The outlet of Muddy Creek into Slippery Rock Creek has been worn down about 40 feet in postglacial time; this outlet is a hanging valley which has a very scenic waterfall, Grant City Falls, known also as Muddy Creek Falls. A few lesser cascades occur between this falls and Slippery Rock Creek. Alpha Falls (391), located about 1.3 miles south in McConnells Mill State Park, has a similar origin but is not as spectacular; it has only a small stream and little water plunging about 50 feet over flat-lying sandstone.
REFERENCES: Bushnell, Kent [19751, McConnells Mill State Park—Slippery Rock Creek Gorge, Pennsylvania Geological Survey, 4th ser., Park Guide 9, pamphlet.PDF with map and photos.
QUADRANGLE: Campbell, Ohio-Pennsylvania
LOCATION: One-half mile east of the Ohio-Pennsylvania border and about 0.7 mile northwest of the village of Hillsville.
REMARKS: The falls are best viewed from near the Pittsburgh and Lake Erie Railroad tracks at the junction with U. S. Route 224. A 50-foot waterfall and a steep-walled valley mark the path of Quakertown Run flowing into the Mahoning River. Waterfalls of this magnitude are very rare in western Pennsylvania.
I. C. White wrote the following in 1879 (p. 194 in reference below): "The run having leaped by a simgle bound into a deep and narrow cañon, bordered on either side by immense vertical and overhanging cliffs of sandstone, passes on down through the same amid the wildest scenery. This locality is a noted resort for picnic parties, since in the deep and narrow recesses of the minature canñon are many attractive nooks where the meridian sun never shines."
The Upper Connoquenessing sandstone (Pottsville Group, Pennsylvanian age) forms the cliff rock of the falls. This sandstone is hard, coarse grained, massive, and white. Immediately under the sandstone is a foot-thick coal named the Quakertown coal for this locality.
Very neat and ornate initials and the date 77 are carved into the rocks at the falls I. C. White studied the geology of this area in the summer of 1877, and he and his assistants may have been responsible for these carvings.
REFERENCES: White, I. C. (1879), The geology Lawrence County, Pennsylvania Geological Survey, 2nd ser., Report of Progress 1877, v. QQ, 336 p.
TOWNSHIP: Slippery Rock and Perry
LOCATION: Immediately west of the Lawrence-Butler County line near Portersville on U. S. Route 19.
REMARKS: The striking scenery of the deep gorge of Slippery Rock Creek flowing through McConnells Mill State Park is the result of the glaciation of this area several tens of thousands of years ago, the park and gorge extend more than 4 miles in length.
At Spillway Falls (18), a large volume of water plunged over the rim of the Homewood Sandstone Member of the Curwensville Formation (Pottsville Group, Pennsylvanian age) with enough energy to quickly enlarge and deepen the gorge. As the ice retreated, more spillways were opened. One of these north of Rose Point, Muddy Creek Falls (19), marks the last discharge channel from glacial Lake Arthur. Here Muddy Creek valley hangs above Slippery Rock Creek; the stream plunges about 100 feet over a very scenic falls.
The Slippery Rock (20), which gave its name to the stream, a town, an oil field, an oil sand, a college, and a local football team, is a slab of Homewood sandstone along the east bank of the creek opposite Camp Allegheny. The rock is very slippery due to an oil seep, which occurs at the point where the stream was forded on foot and horseback by Indians and early settlers.
Slippery Rock Creek Gorge, over 400 feet in depth, has a wealth of rocky cliffs, hanging valleys, and waterfalls. It is a registered National Natural Landmark.
REFERENCES: Bushnell, Kent (1975), McConnells Mill State Park: Slippery Rock Creek Gorge, Pennsylvania Geological Survey, 4th ser., Park Guide 9.
Lytle, Virginia, and Lytle, W. S. (1974), But is there really a Slippery Rock?, Pennsylvania Geology, v. 5, no. 1, p. 4-8.
Lytle, W. S. (1970), Moraine State Park, Pennsylvania Geological Survey, 4th ser., Park Guide 4.