Gull River Formation

Last updated
Gull River Formation
Stratigraphic range: Caradoc
~460.9–449  Ma
Gull River formation1.jpg
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 byV. J. Okulitch
Year defined1939

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]

Contents

Fossil content

Invertebrates

Chelicerates

Chelicerates reported from the Gull River Formation
GenusSpeciesPresenceMaterialNotesImages
Lunataspis L. borealisUpper Member, Kingston, Ontario. [4] 3 specimens (1 adult & 2 juveniles or subadults). [4] A horseshoe crab.

Flora

Acritarchs

Acritarchs reported from the Gull River Formation
GenusSpeciesPresenceMaterialNotesImages
Dicommopalla D. rissaeSouthern Ontario. [5] Also found in the Bobcaygeon Formation.

References

  1. "Gull River formation". Natural Resources Canada. January 9, 2008. Retrieved January 4, 2015.
  2. 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.
  3. 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.
  4. 1 2 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.
  5. 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.