Gull River Formation

Gull River Formation
Stratigraphic range: Caradoc
~460.9–449 Ma
Gull River Formation exposed along the shore of Lake St. John, Ramara
TypeFormation
Unit of
Underlies
OverliesShadow Lake Formation
Lithology
PrimaryLimestone, dolomite
OtherShale, sandstone
Location
Region Ontario
 New York
 Pennsylvania
Country Canada
 United States
Type section
Named forGull 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]

Fossil content

Invertebrates

Chelicerates

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

Acritarchs

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

  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. ^ 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.
  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.


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