Usage:
Ptarmigan Member of Manitou Formation (CO*)
Ptarmigan Chert Member of Manitou Formation (CO*)
Geologic age:
Early Ordovician*
Type section, locality, area and/or origin of name:
Type section: on north wall of cirque, east side of Horseshoe Mountain, about 0.25 mi east of Park Co. line along west extension of line between secs. 7 and 18, T. 10 S., R. 78 W., Park Co., CO. Named from locality near Horseshoe Mountain (Gerhard, 1974).
AAPG geologic province:
Denver basin
Piceance basin
South Park 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 ([ ]).