Guelph Formation

Guelph Formation
Guelph Formation
Stratigraphic range: Silurian
	Stromatolite from the Guelph Formation
Type	Sedimentary
Underlies	Vernon, Lockport Group
Overlies	Eramosa Member
Thickness	160 feet
Lithology
Primary	Dolomite
Location
Region	New York
Country	United States
Type section
Named for	Guelph, Ontario
Named by	William Edmond Logan

Last updated July 03, 2025

The Guelph Formation is a geologic formation in New York and in Ontario, Canada. It preserves fossils dating back to the Silurian period.^[2]

Fossils

Fossils within the formation include:^[1]

Pentamerus occidentalis (Hall)
Megalomus canadensis (Hall)
Murchisonia bivittata (Hall)
M. macrospira (Hall)
M. boydii (Hall)
M. logani
M. longispira
M. uvittata
M. turritiformis
M. tullia
Subulites ventricosus (Hall)
Pleurotomaria solaroides (Hall)
P. elora (Billings)
P. galtensis (Billings)
P. mora
Cyclonema sulcata (Hall)
C. galtensis
C. thysbe
C. psyche
C. depressa
Holopea guelphensis (Billings)
Bellerophon angustata (Hall)
Favosites gothlandica
F. polymorpha
Halysites catenulatus
Columnaria galtensis
Obolus sp.
Orikoceras sp.
Orthoceras darwini
Cyrtoceras arcticameratum
C. Jonesi
Phragmoceras hector
Calymene blumenbachii
Diphyphyllum irregulare
Amplexus laxatus
Rhynchonella sp.
Athyris sp.

References

1 2 3 Logan, W.E., Murray, A., Hunt, T.S., and Billings, E., 1863. Geology of Canada. 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
↑ Guelph, USGS, National Geologic Map Database, Geolex — Unit Summary

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[logan1863-1] 1 2 3 Logan, W.E., Murray, A., Hunt, T.S., and Billings, E., 1863. Geology of Canada. 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

[2] Guelph, USGS, National Geologic Map Database, Geolex — Unit Summary

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