Usage:
Tampico Shale Member of Piper Formation of Ellis Group (MT*,ND*)
Geologic age:
Jurassic, Middle*
Bajocian*
Type section, locality, area and/or origin of name:
Type section (subsurface): depth-interval 3,858 to 3,944 ft, Gulf Oil Company No. 1 Cornwell well, in center SW/4 NE/4 sec. 14, T. 30 N., R. 38 E., Valley Co., northeastern MT. Named from Tampico, west of the type well (Nordquist, 1955).
AAPG geologic province:
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 ([ ]).