Shenandoah National Park Stratigraphy
by Laura Zinck, 2006
Shenandoah National Park
3655 US Hwy 211 East
Luray, Virginia 22835
Approximately 2 million people visit Shenandoah National Park each year. Shenandoah is open all year round, however, facilities are open mid May through October. When visiting the park in December, January or February lodging, food and gas must be found outside of the park. Some services may be available starting in mid March, calling the park to confirm what services are available would be most beneficial (nps).
The facilities in Shenandoah contain everything a visitor would need to make their visit enjoyable. Shenandoah includes visitor centers, bookstores, campgrounds, showers and laundry machines, picnic areas, gift shops, lodges, cabins, restaurants, gas stations, ATMs, waysides, camp stores, a stable, and restrooms (nps).
Shenandoah National Park was established December 26, 1935 (NPS). It is located in Northwest Virginia and includes 300 square miles of the Blue Ridge Mountains in the southern Appalachians, refer to Figure I, II and III (NPS). The park is home to tens of thousands of living creatures ranging from black bear to insects. The majority of the park is covered with hardwood forests, these forests give the Blue Ridge its name due to the faint haze created by photosynthesis (NPS).
Figure 1: Map of the United States, highlighting Virginia taken from http://www.shenandoah.national-park.com
Figure 2: A map of Virginia, showing the location of Shenandoah National Park taken from http://www.shenandoah.national-park.com
Figure 3: Shenandoah National Park taken from http://www.nps.gov/shen/map.htm
The oldest rocks in Shenandoah National Park are granitic and between 1 and 1.2 billion years in age. Bedrock exposures in Shenandoah National Park are very rare, and typically are exposed at road cuts. For the next 500 million years erosion and uplift exposed this granitic rock, some of these exposures can be seen at Old Rag Mountain in the park (www.americanparknetwork.com). The Swift Run Formation is present in Shenandoah National Park, it is late Proterozoic in age and consists of conglomerates, sandstones and pyroclastics caused by stream erosion (Harris and Tuttle). Next came volcanic activity causing basaltic lava flows resulting in a flat plain called the Catoctin Formation, also Proterozoic in age (Harris and Tuttle). An area called “Big Meadows was formed by at least 12 of these lava flows” (www.americanparknetwork.com). The basalts from the lava flows are 570 million years old and metamorphose into greenstones (www.shenandoah.national-park.com). As the lava cooled and contracted cracks and jointing occurred resulting in “Franklin Cliffs, Crescent Rock, and Little Devils Stairs” (www.shenandoah.national-park.com). Sedimentary rocks formed later are also common through out the park. These are typically quartzite, sandstone and phyllite. Cambrian age sedimentary rocks include three formations. The Weverton Formation “lies unconformably on Catoctin rocks” and is 100-500 feet thick (Harris and Tuttle). The Hampton Formation contains the first traces of life, a marine wormlike organism called Skolithos. The Hampton Formation is 1800-2200 feet thick and is composed of clastic rocks. The Erwin Formation overlies the Hampton Formation and contains even more Skolithos. “The Erwin quartzite forms sharp peaks, flatirons, and ridges along the western flanks of the Blue Ridge” (Harris and Tuttle ). Tectonic activity caused the North American and African crustal plates to collide which caused rock layers to tilt and slide creating the Appalachian Mountains (www.americanparknetwork.com). There is evidence of the Taconic orogeny, Acadian orogeny and Alleghany orogeny in Shenandoah National Park. The Taconic orogeny occurred during the Ordovician and was associated with uplift and erosion. The Acadian orogeny occurred during the Devonian and also was associated with uplift and erosion. Last, the Alleghany orogeny occurred during the Permian and Pennsylvanian and was associated with thrust faulting, folding, uplift and erosion (Harris and Tuttle). Wind, water and frost has shaped the Appalachians for nearly 250 million years, causing the magnificent scenery in Shenandoah National Park.
Stratigraphic column if Shenandoah National Park in MSWord and in PDF drawn by Laura Zinck, taken from Harris, Ann G., Tuttle, Esther & Tuttle Sherwood, Geology of National Parks, Kendall/Hunt Publishing Co; Dubuque IA, 1975
Figure 4: A scenic view in Shenandoah National Park taken fromhttp://www.americancelebrationonparade.com/Shenandoah_National_Park.asp
Figure 5: Waterfalls in Shenandoah National Park taken from
Harris, Ann G., Tuttle, Esther & Tuttle Sherwood, Geology
of National Parks, Kendall/Hunt Publishing Co; Dubuque IA, 1975
National Park Service, Shenandoah National Park website, http://www.nps.gov/shen/3b.htm