| Rock Stream Formation | |
|---|---|
| Stratigraphic range: Frasnian | |
| Type | Formation |
| Unit of | Sonyea Group |
| Underlies | Cashaqua Shale |
| Overlies | Pulteney shale |
| Lithology | |
| Primary | Siltstone |
| Other | Shale |
| Location | |
| Region | New York |
| Country | United States |
The Rock Stream Formation (or Rock Stream siltstone [1] ) is a geologic formation in New York. It preserves fossils dating back to the Devonian period.