Collingwood Formation (MI*, PA?, and subsurface of WI*)
Collingwood Member of Lindsay Formation (Canada)
Late Ordovician (Mohawkian)*
(In Canada, age is Mohawkian to Maysvillian.)
Well exposed at Collingwood, on southern shore of Lake Superior, Ontario, Canada (Raymond, 1912).
Appalachian basin?
Michigan basin*
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).