View source for Gull River Formation

{{Infobox rockunit
| name           = Gull River Formation
| image          = Gull River formation1.jpg
| caption        = Gull River Formation exposed along the shore of Lake St. John, [[Ramara]]
| type           = [[Formation (stratigraphy)|Formation]]
| age            = [[Caradoc Series|Caradoc]]<br />~{{Fossil range|460.9|449}}
| period         = Sandbian
| prilithology   = [[Limestone]], [[Dolomite (rock)|dolomite]]
| otherlithology = [[Shale]], [[sandstone]]
| namedfor       = [[Gull River (Balsam Lake)|Gull River]]
| namedby        = V. J. Okulitch
| year_ts        = 1939
| region         = {{Flag|Ontario}}<BR>{{Flag|New York}}<BR>{{Flag|Pennsylvania}}
| country        = {{Flag|Canada}}<BR>{{Flag|United States}}
| coordinates    =
| unitof         = * [[Simcoe Group]]
* [[Black River Group]]
| subunits       =
| underlies      = * [[Bobcaygeon Formation]]
* [[Coboconk Formation]]
| overlies       = [[Shadow Lake Formation]]
| thickness      =
| extent         =
| area           =
| map            =
| map_caption    =
}}
The '''Gull River Formation''' is a [[geological formation]] of Middle [[Ordovician]] age (Caradoc [[Stage (stratigraphy)|Stage]]), which outcrops in [[Ontario]], [[Canada]].<ref name=weblex>{{cite web|title=Gull River formation|url=http://weblex.nrcan.gc.ca/html/006000/GSCC00053006056.html|publisher=[[Natural Resources Canada]]|accessdate=January 4, 2015|date=January 9, 2008}}</ref> [[Lithology|Lithologically]], the formation is dominated by light grey to brown [[limestone]]s and greenish gray [[Dolomite (rock)|dolomite]]s with thin [[shale]] and [[sandstone]] interlayers.<ref name=OGS1>{{cite book|last1=Armstrong|first1=Derek K.|last2=Dodge|first2=J. E. P.|title=Paleozoic Geology of Southern Ontario|date=2007|publisher=[[Ontario Geological Survey]]|isbn=978-1-4249-4526-9|pages=4|url=http://maps.niagararegion.ca/Metadata/md/DocumentUpload/2007-08-08%2014-44-38.pdf}}</ref><ref name=OGS2>{{cite book|last1=Armstrong|first1=D. K.|title=Paleozoic Geology of the Northern Lake Simcoe Area, South-Central Ontario|date=2000|publisher=[[Ontario Geological Survey]]|isbn=978-0--7778--9451--4|pages=9–15|url=http://www.geologyontario.mndmf.gov.on.ca/mndmfiles/pub/data/imaging/OFR6011/OFR6011.pdf}}</ref>

==Fossil content==
===Invertebrates===
====Chelicerates====
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | '''[[Chelicerate]]s reported from the Gull River Formation'''
|-
! Genus !! Species !! Presence 
!'''Material'''!! Notes !! Images
|-
| ''[[Lunataspis]]''
|''L. borealis''
| Upper Member, [[Kingston, Ontario]].<ref name=":0">{{Cite journal |last1=Lamsdell |first1=James C. |last2=Isotalo |first2=Phillip A. |last3=Rudkin |first3=David M. |last4=Martin |first4=Markus J. |date=October 2022 |title=A new species of the Ordovician horseshoe crab Lunataspis |url=https://www.cambridge.org/core/journals/geological-magazine/article/new-species-of-the-ordovician-horseshoe-crab-lunataspis/E198745336B0E124E34966425F35FB02 |journal=Geological Magazine |language=en |pages=1–5 |doi=10.1017/S0016756822000875 |s2cid=252723542 |issn=0016-7568|doi-access=free }}</ref>
|3 specimens (1 adult & 2 juveniles or subadults).<ref name=":0" />
| A [[Xiphosura|horseshoe crab]].
| 
|-
|}

===Flora===
====Acritarchs====
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | '''[[Acritarch]]s reported from the Gull River Formation'''
|-
! Genus !! Species !! Presence 
!'''Material'''!! Notes !! Images
|-
| ''[[Dicommopalla]]''
|''D. rissae''
| Southern Ontario.<ref>{{Cite journal |last1=Bunner |first1=Wendy D. |last2=Legault |first2=J. A. |date=1989 |title=A New Species of Dicommopalla (Acritarcha) from the Middle Ordovician Simcoe Group of Southern Ontario, Canada |url=https://www.jstor.org/stable/3687532 |journal=Palynology |volume=13 |pages=57–62 |doi=10.1080/01916122.1989.9989354 |jstor=3687532 |issn=0191-6122}}</ref>
|
| Also found in the [[Bobcaygeon Formation]].
| 
|-
|}
*

==References==
{{reflist}}
[[Category:Ordovician Ontario]]
[[Category:Ordovician southern paleotemperate deposits]]
[[Category:Ordovician southern paleotropical deposits]]
[[Category:Geologic formations of Ontario]]


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