Larrys Creek - Geology

Geology

Larrys Creek is in a sandstone, limestone, and shale mountain region, with the source in the dissected Allegheny Plateau and the mouth in the Ridge-and-valley Appalachians. The southern part of the Larrys Creek watershed has sedimentary surface rocks from the Devonian period, with a large area from the Mississippian period in the north of the watershed and a small Pennsylvanian period region within this area. The Cogan House anticline runs north of and parallel to the upper part of the creek. Iron ore within the watershed was mined south of Salladasburg and along Canoe Run in the 19th century; there are also deposits on Puterbaugh Mountain.

Larrys Creek is in a narrow valley formed by mountains and hills, with steep to moderate slopes. The channel pattern is regular, with a dendritic drainage pattern. After leaving its source, the creek turns to flow southwest along the northern edge of Green Mountain, turns south into the State Game Lands at Buckhorn Mountain, and flows south along the western edge of Coal Mountain. The only named peak on the west bank of Larrys Creek itself is Harris Point, where it leaves the dissected Allegheny Plateau.

The Second Fork flows south along the eastern side of Henson Ridge, then east of Puterbaugh Mountain. The only named peak on the east bank of the Second Fork is Clapp Point, which marks the boundary of the dissected plateau and is southwest of Harris Point. The First Fork flows past the southwest edge of Little Round Top and then continues on the southwest side of Puterbaugh Mountain. Fishery Point is at the southern end of the Allegheny Plateau, just west of the First Fork. The three features named Point are each part of the Allegheny Front, the edge of the Allegheny Plateau.

The Larrys Creek watershed has two deposits of low volatile bituminous coal along Roaring Run and a small, deep natural gas field. A potentially large source of natural gas is the Marcellus Shale, which lies 1.5 to 2.0 miles (2.4 to 3.2 km) below the surface here and stretches from New York through Pennsylvania to Ohio and West Virginia. Estimates of the total natural gas in the black shale from the Devonian era range from 168 to 516 trillion cubic feet (4.76 to 14.6 trillion m3), with at least 10 percent considered recoverable. In November 2007, drilling within the Larrys Creek watershed started in Mifflin Township, just west of Salladasburg, with a 1.5 miles (2.4 km) deep well. A second well was drilled in Mifflin Township in December 2007, and by February 2008 every well drilled in Lycoming County was producing natural gas. The Marcellus Shale requires special techniques to fracture the rock and release the gas, including pumping sand and water into the well, and, in some cases, horizontal drilling.