- Usage in publication:
-
- Double Point dacite*
- Modifications:
-
- Named
- Dominant lithology:
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- Dacite
- Rhyodacite
- AAPG geologic province:
-
- Aleutian Islands province
- Alaska Southwestern region
Summary:
Named for exposures north of Double Point in southwest coast of Little Sitkin Island, Rat Islands group, Aleutian Islands, AK. Largest outcrop extends from Double Point northeastward to drainage of Williwaw Cove stream and includes present caldera scarp. Shown on geologic map of Little Sitkin Island. Consists of flows of light- to dark-gray glassy to lithoidal rocks containing many small plagioclase phenocrysts. Most of rock is light-gray high-silica dacite but ranges, locally, to rhyodacite. Forms volcanic pile 3000 ft high. Overlaps Williwaw Cove (new), Sitkin Point (new), and East Point (new) formations. Underlies Patterson Point formation (new). Age is middle Quaternary based on its partly dissected lava-flow topography and stratigraphic 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 ([ ]).