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National Geologic Map Database

Geologic Unit: Interlake

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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).