Tuscarora Sandstone

The Silurian Tuscarora Formation — also known as Tuscarora Sandstone or Tuscarora Quartzite — is a mapped bedrock unit in Pennsylvania, Maryland, West Virginia, and Virginia, US.

The Tuscarora is a thin- to thick-bedded fine-grained to coarse-grained orthoquartzite. It is a white to medium-gray or gray-green subgraywacke, sandstone, siltstone and shale, cross-stratified and conglomeratic conglomerate in parts, containing a few shale interbeds.

Details of the type locality and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database.

The Tuscarora and its lateral equivalents are the primary ridge-formers of the Ridge-and-Valley Appalachians in the eastern United States It is typically 935 feet thick in Pennsylvania, and in Maryland varies from 60 feet to 400 feet thick from east to west.

The Tuscarora Formation is commonly exposed on various ridge crests and in many water gaps in the Ridge and Valley physiographic province of the Appalachians of Pennsylvania, Maryland, and West Virginia, particularly along the Wills Mountain Anticline.

In Pennsylvania, the Tuscarora is exposed along US 30 on the north and south sides of the Narrows in central Bedford County, where it is nearly vertical. It is also well-exposed in the core of Jack's Mountain in Jack's Narrows, where the Juniata River cuts through the mountain, just west of Mount Union. The Standing Stone Trail traverses this cut, and many of the "Thousand Steps" here are Tuscarora quartzite.

In Maryland, the National Road (US 40) passes arched Tuscarora sandstone outcrops in the Cumberland Narrows in Allegany County.

In West Virginia, the River Knobs along the North Fork of the South Branch of the Potomac River in Pendleton County include dramatic outcrops of nearly vertical Tuscarora sandstone. Some of the better known of these exposures are Seneca Rocks, Champe Rocks, Judy Rocks, and Nelson Rocks. These cliffs are clearly visible along U.S. Route 33 and West Virginia Routes 28 and 55. North Fork Mountain, to the east of the River Knobs, is a long Ridge and Valley anticline ridge capped by Tuscarora sandstone.