| Keyser Formation | |
|---|---|
| Stratigraphic range: Pridoli-Lochkovian[1] | |
 Outcrop of the Keyser Formation on U.S. Route 522 in Fulton County, Pennsylvania, north of Warfordsburg | |
| Type | Sedimentary |
| Unit of | Helderberg Group |
| Sub-units | Byers Island, Jersey Shore & La Vale Members |
| Underlies | New Creek Limestone and Old Port Formation |
| Overlies | Tonoloway Formation |
| Thickness | 33 m (108 ft) at Allegheny Furnace |
| Lithology | |
| Primary | Limestone |
| Location | |
| Coordinates | 38°18′N 79°36′W / 38.3°N 79.6°W |
| Approximate paleocoordinates | 36°18′S 41°30′W / 36.3°S 41.5°W |
| Region | Pennsylvania, Maryland, Virginia, West Virginia |
| Country |  United States |
| Extent | Appalachian Mountains |
| Type section | |
| Named for | Keyser, West Virginia |
| Named by | E. O. Ulrich |
| Year defined | 1911[2] |
  Keyser Formation (the United States)  Keyser Formation (Virginia) | |
The Late Silurian to Early Devonian Keyser Formation is a mapped limestone bedrock unit in Pennsylvania, Maryland, Virginia, and West Virginia.
- ^ Paleozoic Sedimentary Successions of the Virginia Valley & Ridge and Plateau
- ^ Ulrich, E.O., 1911, Revision of the Paleozoic systems: Geological Society of America Bulletin, v. 22, p. 281-680