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National Geologic Map Database

Geologic Unit: Fuson

Usage:

Fuson Member of Lakota Formation of Inyan Kara Group (SD*,WY*-recognized locally in Black Hills area)
Fuson Shale Member of Cloverly Formation (WY*-recognized locally in Bighorn basin)
Fuson Shale (NE*, and subsurface of ND*,MT*)
[?] Fuson Shale of Inyan Kara Group (SD*,WY*-recognized locally in Black Hills area)
[?] Fuson Formation of Inyan Kara Group (MT,SD*,WY*)
[?] Fuson Formation of Cloverly Group (MT)
[?] Fuson Shale of Cloverly Group (MT)
[?] Fuson Formation of Dakota Group (ND)
[?] Fuson Shale of Dakota Group (NE)
[?] Fuson Formation (MT*,ND*)


Geologic age:

Early Cretaceous (Aptian to Albian)*


Type section, locality, area and/or origin of name:

Named from striking exposures in Fuson Canyon [on east side of Black Hills, SD] (Darton, 1901).
Type section (base not exposed): measured in a cliff at apex of sharp bend in Dry Creek, Fuson Canyon, in SE/4 NE/4 SW/4 sec. 36, T. 5 S., R. 6 E., Custer Co., SD (Waage, 1959).
Reference section (Fuson Member of Lakota Formation): on east bank of Cheyenne River, in SW/4 NW/4 sec. 2, T. 9 S., R. 4 E., Cascade Springs quadrangle, Fall River Co., SD (Post and Bell, 1961).


AAPG geologic province:

Chadron arch*
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 ([ ]).