Appalachian Mountain Section
Ridge and Valley Province

Appalachian Mountain Section showing geology and shaded relief


The Appalachian Mountain Section consists of numerous, long, narrow mountain ridges separated by narrow to wide valleys. The tops of the ridges are always several hundred feet higher than the adjacent valley, and some ridges are more than a thousand feet higher than the adjacent valley. Elevations in the Section range from 440 feet to 2,775 feet. Very tough sandstones occur at the crests of the ridges. Relatively soft shales and siltstones occur in most of the valleys. Some of the valleys are underlain by limestone and dolomite. At one time many millions of years ago the rocks in this Section were flat lying. Then they were compressed toward the northwest by immense pressure coming from the southeast. This pressure buckled the rocks into long, linear folds called anticlines (upward-buckled rocks) and synclines (downward-buckled rocks). Erosion of the rocks in these adjacent anticlines and synclines created the ridges and valleys of the Appalachian Mountain Section. The shales and siltstones are eroded more easily than the sandstones. Thus, as erosion proceeds, the slowly eroded sandstones form ridges while the shales and siltstones are eroded more rapidly to form the lowlands.

The Appalachian Mountain Section occurs in central Pennsylvania where it is the topographic expression in parts of 14 counties including Bedford, Blair, Centre, Clinton, Cumberland, Franklin, Fulton, Huntingdon, Juniata, Lycoming, Mifflin, Perry, Snyder, and Union.

Typical topography can be viewed almost anywhere within the Section. There are many excellent views along US Routes 22 and 322 between Harrisburg and Altoona or State College; along Interstate 76 (Pennsylvania Turnpike) between Blue Mountain Tunnel and Allegheny Tunnel; and along many roads that are in the valleys parallel to the ridges.

Some of the Outstanding Scenic Geological Features in the Section include: Arch Spring, Big Knob, near Big Knob - Little Knob;Big Round Top, near Big Round Top - Burns Valley Overlook and Big Spring; Birmingham Fault, Birmingham Window, Black Spring, Blue Knob, Butler Knob, Cape Horn, Celestine Locality, Chalybeate Spring, Chimney Rocks, Concord Narrows, Crystal Spring, East Waterford Narrows, Entriken Bridge Overlook, Glade Pike Vistas, Gobblers Knob, Hogback, Horshoe Curve, Indian Chair, Indian Chief Rock, Jacks Narrows, near Jacks Narrows - Captain Jacks Spring; Limestone Spring, Lowery Knob, Magnesia Iron Spring, Magnesia Spring, Nancys Saddle, Parnell Knob, Prayer Rock, Pulpit Rocks, Roaring Spring, Shaefer Overlook, Sidneys Knob, Sinking Valley Lead-Zinc Mines, Spring Meadow Spring, at Trough Creek Gorge - Balanced Rock, Ice Cave, and Copperas Rock; The Kettle, Trough Creek Gorge, Tuscarora Summit, and White Sulphur Spring, and between Entriken Bridge Overlook and Raystown Dam - Coffee Run Overlook, Hawns Overlook, and Ridenour Overlook

Scenery of the Section can be experienced by visiting one of the many State Parks including Fowlers Hollow, Bald Eagle, Big Spring, Buchanan's Birth Place, Canoe Creek, Colonel Denning, Cowans Gap, Greenwood Furnace, Mccall Dam, Penn Roosevelt, Poe Paddy, Poe Valley, Ravensburg, Raymond B. Winter, Reeds Gap, Sand Bridge, Trough Creek, Warriors Path, and Whipple Dam. Look for more information on these state parks at the State Parks web page.

State Forest Natural Areas include Sweet Root, Pine Ridge, Hemlocks, Frank E. Masland, Jr., and Little Juniata.

While travelling in the Section, have a picnic at one of the State Forest Picnic Areas which include Alan Seeger, Sweet Root, Blankley, Sideling Hill, Bear Valley, Colerain, and Pine Hill.