Unit is named the Owl Creek Formation. Composed of olivine basalt flows which are locally highly vesicular and some flows have large tabular labradorite crystals similar to "Steens" basalts to the north. Has average thickness of 20 ft. Stratigraphic chart shows unit overlies the Squaw Peak Formation; underlies the Patterson Tuff. A K-Ar age of about 13.7 Ma was obtained from one of the flows (Duffield, personal commun.). Age is Miocene.
[NOTE: The Department of the Interior's Secretarial Order 3404, issued on November 19, 2021, formally identifies the term “squaw” as derogatory. That Order will create a federal Derogatory Geographic Names Task Force, to find replacement names for geographic features in use by federal agencies. We’re awaiting guidance from the Task Force, and will then take the appropriate actions.]
Source: GNU records (USGS DDS-6; Menlo GNULEX).
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 ([ ]).