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| Catskill Group | |
|---|---|
| Stratigraphic range: Devonian | |
 Outcrop of the Irish Valley Member of the Catskill Formation along the Horseshoe Curve, Blair County, Pennsylvania | |
| Type | sedimentary |
| Underlies | Rockwell Formation, Huntley Mountain Formation, Pocono Formation, Spechty Kopf Formation |
| Overlies | Foreknobs Formation, Lock Haven Formation, Trimmers Rock Formation |
| Thickness | Up to 10,000 ft (3,000 m) |
| Lithology | |
| Primary | Sandstone |
| Other | Siltstone, shale |
| Location | |
| Region | Appalachian Mountains |
| Country | United States |
| Extent | Pennsylvania, New York (state) |
| Type section | |
| Named for | Catskill Mountains, New York |
The Devonian Catskill Group or the Catskill Clastic wedge is a unit of mostly terrestrial sedimentary rock found in Pennsylvania and New York. Minor marine layers exist in this thick rock unit (up to 10,000 feet (3,000 m)). It is equivalent to the Hampshire Formation of Maryland, West Virginia, and Virginia.
The Catskill is the largest bedrock unit of the Upper Devonian in northeast Pennsylvania and the Catskill region of New York, from which its name is derived. The Pocono Mountains of Pennsylvania are largely underlain by this unit as well. The rocks of the Catskill are predominantly red sandstone, indicating a large-scale terrestrial deposition during the Acadian orogeny. Many beds are cyclical in nature, preserving the record of a dynamic environment during its approximately 20 million years of deposition.