Catoctin Formation
| Catoctin Formation | |
|---|---|
| Stratigraphic range: Ediacaran | |
| Type | Formation |
| Underlies | Chilhowee Group |
| Overlies | Basement Rock |
| Thickness | 100-400 Feet |
| Location | |
| Region | Virginia, Maryland, and Pennsylvania |
| Country | United States |
| Type section | |
| Named for | Its exposure on Catoctin Mountain |
| Named by | Arthur Keith |
Geological Map of the Catoctin Formation shown in blue and other formations associated with it. | |
The Catoctin Formation is a geologic formation that expands through Virginia, Maryland, and Pennsylvania. It dates back to the Precambrian and is closely associated with the Harpers Formation, Weverton Formation, and the Loudoun Formation. The Catoctin Formation lies over a granitic basement rock and below the Chilhowee Group making it only exposed on the outer parts of the Blue Ridge. The Catoctin Formation contains metabasalt, metarhyolite, and porphyritic rocks, columnar jointing, low-dipping primary joints, amygdules, sedimentary dikes, and flow breccias. Evidence for past volcanic activity includes columnar basalts and greenstone dikes.