| Gull River Formation | |
|---|---|
| Stratigraphic range: Caradoc ~ | |
 Gull River Formation exposed along the shore of Lake St. John, Ramara | |
| Type | Formation |
| Unit of | |
| Underlies | |
| Overlies | Shadow Lake Formation |
| Lithology | |
| Primary | Limestone, dolomite |
| Other | Shale, sandstone |
| Location | |
| Region |  Ontario New York Pennsylvania |
| Country |  Canada United States |
| Type section | |
| Named for | Gull River |
| Named by | V. J. Okulitch |
| Year defined | 1939 |
The Gull River Formation is a geological formation of Middle Ordovician age (Caradoc Stage), which outcrops in Ontario, Canada.[1] Lithologically, the formation is dominated by light grey to brown limestones and greenish gray dolomites with thin shale and sandstone interlayers.[2][3]
- ^ "Gull River formation". Natural Resources Canada. January 9, 2008. Retrieved January 4, 2015.
- ^ Armstrong, Derek K.; Dodge, J. E. P. (2007). Paleozoic Geology of Southern Ontario (PDF). Ontario Geological Survey. p. 4. ISBN 978-1-4249-4526-9.
- ^ Armstrong, D. K. (2000). Paleozoic Geology of the Northern Lake Simcoe Area, South-Central Ontario (PDF). Ontario Geological Survey. pp. 9–15. ISBN 978-0--7778--9451--4.