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National Geologic Map Database

Geologic Unit: Orellan

Usage:

Orellan age*


Geologic age:

Tertiary*
Oligocene, early


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

Name based on Orella Member of Brule Formation, type locality, Orella, northwestern NE (Wood and others, 1941).


AAPG geologic province:

North America


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 ([ ]).