Guelph Formation Explained

Guelph Formation
Type:	Sedimentary
Age:	Silurian
Prilithology:	Dolomite
Namedfor:	Guelph, Ontario
Namedby:	William Edmond Logan^[1]
Underlies:	Vernon, Lockport Group
Overlies:	Eramosa Member
Thickness:	160 feet

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.

Notes and References

1. 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. https://ngmdb.usgs.gov/Geolex/Units/Guelph_1916.html Guelph