/Sand Bay lava flows of Sand Bay volcanics. Name proposed for upper part of Sand Bay Volcanics; not adopted by the USGS. Consists of porphyritic flows, including andesite, olivine andesite, and andesite flow-breccia, and basalt. Colors range from black through purplish gray and reddish gray to light gray. Most flows are medium grained, but few are very fine grained. Platy lavas are rare; most rocks show little or no flow structure. Columnar jointing is common. Vesicular flows are rare. Lavas dip gently south or southeast and thicken toward center of island and reach aggregate thickness of 400 feet on "Triple Divide Peak" at head of Middle Yoke Valley. Overlies /Sand Bay agglomerate (new). Underlies Great Sitkin volcanics (new). Age is considered late Tertiary based on regional stratigraphic relations.
Occurs in southern part of Great Sitkin Island in central part of Aleutian Islands. [Type locality not designated. Named from Sand Bay in northeast part of Adak 1:250,000 quadrangle, Aleutian Islands, southwestern AK.]
[Use of same name for a unit and its constituents conflicts with nomenclature guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021); should have been named as member with different geographic designation.]

Source: Modified from GNU records (USGS DDS-6; Menlo GNULEX).

Pg. 28-29, pl. 5. [†Sand Bay lava flows considered abandoned. The upper sequence of andesitic and basaltic lavas of the Sand Bay volcanics, previously called Sand Bay lava flows by Simons and Mathewson (1947), are herein referred to as "lava flows."]

Source: Interpreted from publication.