National Geologic Map Database
Geologic Unit: Bertram
Usage:
Geologic age:
Type section, locality, area and/or origin of name:
AAPG geologic province:
Usage:
Bertram Formation of Wapsipinicon Group (IA)
Geologic age:
early Middle Devonian (Eifelian)
Type section, locality, area and/or origin of name:
Named from Bertram, Linn Co., eastern IA (Norton, 1895).
AAPG geologic province:
Iowa shelf
Wisconsin arch
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 ([ ]).