| Wissahickon Formation | |
|---|---|
| Stratigraphic range: Ediacaran to Early Cambrian (Depositional) | |
 A hand sample of the type Wissahickon from the banks of the Wissahickon Creek | |
| Type | Geological formation |
| Sub-units | Mt. Cuba, Doe Run schist, Laurels schist, Greystone schist |
| Underlies | Hardyston Quartzite |
| Overlies | Chestnut Hill Formation |
| Thickness | unknown |
| Lithology | |
| Primary | Schist |
| Other | Gneiss and quartzite |
| Location | |
| Region | Piedmont of eastern North America |
| Country | United States |
| Extent | Southeastern Pennsylvania, northern Delaware, Northeastern Maryland |
| Type section | |
| Named for | The Wissahickon Creek |
The Wissahickon Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and Delaware. It is named for the Wissahickon gorge in Fairmount Park, Philadelphia.
In Maryland formations, the term "Wissahickon" is no longer used. Rocks in this classification have since been divided into several units, such as Lower Pelitic Schist and Prettyboy Schist.[1]