Usage:
Interlake Group (MT,ND)
Interlake Formation (MT*,ND*,SD*,WY*)
Interlake Formation of Elk Point Group (ND)
(Use of †Interlake Formation abandoned by the Canada Geol. Survey.)
Subunits:
GROUP STATUS (alphabetical): Cedar Lake Formation (MT?,ND), Fife Lake Formation (MT?,ND), Grondale Formation (MT,ND), Guernsey Formation (MT,ND), Mendenhall Formation (MT,ND), Missouri Breaks Formation (MT?,ND), Sherven Formation (MT?,ND), Strathclair Formation (MT,ND).
Geologic age:
Ordovician, Late*
Silurian*
Type section, locality, area and/or origin of name: (See Canadian Lexicon)
Interlake area of Manitoba, Canada (CSPG Western Canada Lexicon).
AAPG geologic province:
Powder River basin*
Williston 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 ([ ]).