Tuscarora Quartzite

The big rock formations of the North Fork Valley of eastern West Virginia, such as Champe Rocks, Seneca Rocks and Nelson Rocks, are formations of Tuscarora Quartzite. This is an extremely hard metamorphic rock, ranging in color from a nearly translucent white, to gray, to pink and orange. Laid down as sediment on a sea floor 440 million years ago, the Tuscarora is about 250 feet thick in West Virginia. It is the same rock which makes up the famous crags of the Shawangunk range in New York State. In the "Gunks", the rock appears in horizontal layers, just as it was laid down on the ancient seabed. Along the hills and ridges east of the North Fork River in West Virginia - the "River Knobs" - it has done something different. Here, the quartzite layer was literally turned on end by enormous geological forces during the formation of the Appalachian Mountains some 230 million years ago. A folding of the Earth's crust forced this layer - and the surrounding strata - into enormous arches, miles wide. The River Knobs trace the western wall of this arch, or "anticline", where the Tuscarora was turned a full 90 degrees from horizontal to vertical. Over time, erosion stripped away the softer rock covering the arch, and finally the dome of the arch itself. The tough quartzite of the western walls resisted this process, leaving soaring "fins" - narrow vertical plates of exposed rock. These unique formations are visible from Highways 55 and 33 throughout the North Fork Valley. Farther east, along the top of North Fork Mountain, the horizontal strata of the far slope of the Tuscarora anticline are still visible. Another interesting chapter of this story was recently given to us courtesy of Roy Sites, a geologist with the State of Virginia. Many of quartzite outcroppings seen along the River Knobs may be seen as not one, but two parallel fins. These include Champe and Nelson Rocks. The explanation for this is that, during the rise of the Appalachians, the same forces which formed the anticline caused the Tuscarora to fault or rupture, with the upper layer sliding over and overlapping the lower. As the top of the arch wore away, two fins were left. Nelson is considered one of the best examples of the faulted Tuscarora. Seneca Rocks is a much thicker, monolithic formation. This is because, at Seneca, the rock did not fault cleanly into two layers but rolled over on itself. From Roy Gap, looking north, this effect is clearly visible in the curving layers of rock surrounding the large cave in the south end of Seneca.

©2002 Nelson Rocks Preserve