Guelph Formation

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

Fossils
Fossils within the formation include:
 * 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.