- Usage in publication:
-
- Crater Creek basalt*
- Modifications:
-
- Named
- Dominant lithology:
-
- Volcaniclastics
- Volcanics
- Tuff
- AAPG geologic province:
-
- Alaska Southwestern region
- Aleutian Islands province
Summary:
[Named for Crater Creek in east-central part of Umnak 1:250,000 quad, southwest AK.] [no type designated] Occurs in gorge of Crater Creek and in walls of Okmok Caldera. Consists of series of basalt flows and minor interbedded tuff and tuff-breccia layers; individual flows range from 10 to 70 feet thick. Maximum thickness is 1,300 feet. [Unconformably?] overlies Tulik and Ashishik basalts (both new); [unconformably?] underlies Tanak volcanics (new). Age given as Tertiary and Quaternary [based on regional stratigraphic relations].
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Crater Creek basalt*
- Modifications:
-
- Age modified
- Revised
- AAPG geologic province:
-
- Alaska Southwestern region
- Aleutian Islands province
Summary:
Stratigraphically restricted to sequence of basalt flows exposed in Crater Creek gorge and in north wall of Okmok Caldera to the west. Now excludes formerly assigned uppermost aphyric basalt flows on outer slopes of Okmok Volcano (now assigned to Ashishik basalt). Consists of at least 15 separate flows with total exposed thickness of 500 ft. Unconformably overlies Ashishik basalt; [unconformably?] underlies Okmok volcanics. Age given as Pleistocene to early Holocene [based on regional relations].
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 ([ ]).