Usage:
Horseshoe Shale Member of Amsden Formation (WY*)
Geologic age:
Mississippian, Late*
Chesterian, late*
Pennsylvanian, Early*
Morrowan*
Type section, locality, area and/or origin of name:
Type section: in SE/4 sec. 33, T. 57 N., R. 87 W., Sheridan Co., WY (Mallory, 1967).
Reference sections: (1) in lower Tensleep Canyon, station 190, in T. 47 N., R. 88 W., Washakie Co., WY (Mallory, 1967); (2) in SW/4 sec. 34, T. 57 N., R. 87 W., Sheridan Co., WY (Sando and others, 1975).
AAPG geologic province:
Powder River basin*
Bighorn basin*
Yellowstone province*
Wind River basin*
Green River 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 ([ ]).