Gull River Formation
| 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]
Fossil content[edit]
Invertebrates[edit]
Chelicerates[edit]
| Chelicerates reported from the Gull River Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Lunataspis | L. borealis | Upper Member, Kingston, Ontario.[4] | 3 specimens (1 adult & 2 juveniles or subadults).[4] | A horseshoe crab. | |
Flora[edit]
Acritarchs[edit]
| Acritarchs reported from the Gull River Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Dicommopalla | D. rissae | Southern Ontario.[5] | Also found in the Bobcaygeon Formation. | ||
References[edit]
- ^ "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.
- ^ a b Lamsdell, James C.; Isotalo, Phillip A.; Rudkin, David M.; Martin, Markus J. (October 2022). "A new species of the Ordovician horseshoe crab Lunataspis". Geological Magazine: 1–5. doi:10.1017/S0016756822000875. ISSN 0016-7568. S2CID 252723542.
- ^ Bunner, Wendy D.; Legault, J. A. (1989). "A New Species of Dicommopalla (Acritarcha) from the Middle Ordovician Simcoe Group of Southern Ontario, Canada". Palynology. 13: 57–62. doi:10.1080/01916122.1989.9989354. ISSN 0191-6122. JSTOR 3687532.
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