# Guelph Formation

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{{Short description|Geological formation in New York and in Ontario, Canada}}
{{Infobox rockunit
| name           = Guelph Formation
| image          = Guelph Formation stromatolite.jpg
| caption        = [Stromatolite](/source/Stromatolite) from the Guelph Formation 
| type           = [Sedimentary](/source/Sedimentary_rock)
| age            = [Silurian](/source/Silurian)
| prilithology   = [Dolomite](/source/Dolomite_(rock))
| otherlithology =
| namedfor       = [Guelph](/source/Guelph), Ontario
| namedby        = [William Edmond Logan](/source/William_Edmond_Logan)<ref name=logan1863>Logan, W.E., Murray, A., Hunt, T.S., and Billings, E., 1863. Geology of Canada. [https://archive.org/details/reportofprogress00geolrich/page/n7/mode/2up Report of Progress from its Commencement to 1863]; Geological Survey of Canada, 983 p. [accompanied by an Atlas of Maps and Sections.] doi:10.4095/123563</ref>
| region         = [New York](/source/New_York_(state))
| country        = [United States](/source/United_States)
| coordinates    =
| unitof         =
| subunits       =
| underlies      =[Vernon](/source/Vernon_Formation), [Lockport Group](/source/Lockport_Group)
| overlies       =[Eramosa Member](/source/Eramosa_Member)
| thickness      =160 feet<ref name=logan1863/>
| extent         =
| area           =
| map            =
| map_caption    =
}}

The '''Guelph Formation''' is a [geologic formation](/source/Formation_(stratigraphy)) in [New York](/source/New_York_(state)) and in [Ontario](/source/Ontario), Canada. It preserves [fossils](/source/fossils) dating back to the [Silurian](/source/Silurian) [period](/source/Period_(geology)).<ref>[https://ngmdb.usgs.gov/Geolex/Units/Guelph_1916.html Guelph], [USGS](/source/USGS), National Geologic Map Database, Geolex — Unit Summary</ref>

==Fossils==
Fossils within the formation include:<ref name=logan1863/>
*''[Pentamerus](/source/Pentamerus) occidentalis'' (Hall)
*''[Megalomus](/source/Megalomastomatidae) canadensis'' (Hall)
*''[Murchisonia](/source/Murchisoniidae) bivittata'' (Hall)
*''M. macrospira'' (Hall)
*''M. boydii'' (Hall)
*''M. logani''
*''M. longispira''
*''M. uvittata''
*''M. turritiformis''
*''M. tullia''
*''[Subulites](/source/Subulites) ventricosus'' (Hall)
*''[Pleurotomaria](/source/Pleurotomaria) solaroides'' (Hall)
*''P. elora'' (Billings)
*''P. galtensis'' (Billings)
*''P. mora''
*''Cyclonema sulcata'' (Hall)
*''C. galtensis''
*''C. thysbe''
*''C. psyche''
*''C. depressa''
*''[Holopea](/source/Holopea) guelphensis'' (Billings)
*''[Bellerophon](/source/Bellerophon_(genus)) angustata'' (Hall)
*''[Favosites](/source/Favosites) gothlandica''
*''F. polymorpha''
*''[Halysites](/source/Halysites) catenulatus''
*''[Columnaria](/source/Columnaria) galtensis'' 
*''Obolus sp.''
*''Orikoceras sp.''
*''[Orthoceras](/source/Orthoceras) darwini''
*''[Cyrtoceras](/source/Cyrtoceras) arcticameratum'' 
*''C. Jonesi''
*''[Phragmoceras](/source/Phragmoceratidae) hector''
*''[Calymene](/source/Calymene) blumenbachii''
*''Diphyphyllum irregulare''
*''Amplexus laxatus''
*''[Rhynchonella](/source/Rhynchonella) sp.''
*''[Athyris](/source/Athyris) sp.''

==References==
{{reflist}}

Category:Silurian geology of New York (state)
Category:Geologic formations of New York (state)
Category:Silurian Ontario
Category:Geologic formations of Ontario

{{NewYork-geologic-formation-stub}}

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Adapted from the Wikipedia article [Guelph Formation](https://en.wikipedia.org/wiki/Guelph_Formation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Guelph_Formation?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.