| Old Port Formation | |
|---|---|
| Stratigraphic range: Early Devonian | |
 Ridgeley Member of the Old Port Formation | |
| Type | sedimentary |
| Unit of | Helderberg Group |
| Sub-units | Ridgeley, Shriver, Mandata, Corriganville, and New Creek Members |
| Underlies | Onondaga Formation |
| Overlies | Keyser Formation |
| Thickness | 150 to 190 ft (Mifflintown Quadrangle in PA)[1] |
| Lithology | |
| Primary | limestone, sandstone |
| Other | chert, shale |
| Location | |
| Region | Appalachian Mountains |
| Extent | Pennsylvania, Maryland, Virginia, West Virginia |
| Type section | |
| Named by | Conlin and Hoskins, 1962[1] |
The Devonian Old Port Formation is a mapped bedrock unit in Pennsylvania, USA. Details of the type section 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.[2] Current nomenclature usage by U.S. Geological Survey restricts the name Old Port Formation to Pennsylvania, but correlative units are present in adjacent states.[3]
- ^ a b Conlin, R.R., and Hoskins, D.M., 1962, Geology and mineral resources of the Mifflintown quadrangle, Pennsylvania: Pennsylvania Geological Survey Topographic and Geologic Atlas, 4th series, 126, 46 p., scale 1:24,000
- ^ "National Geologic Map Database".
- ^ "Geolex — OldPort".