The bimodal composition of this deposit is quite apparent in this shot of Dana framing a photo at The Pinnacles.
An article and
an abstract referred to me by
@Volcanologist and
@eruptionsblog, respectively, may be of interest to those wanting more detailed information. Among other things, those two sources have clarified the compositions of the two phases: the lighter is rhyodacite, and the darker is andesite. The article, maddeningly, flaunts the term "supereruption," which I abhor, but the discussion is good. The abstract is dense (as they tend to be), but useful, and focused specifically on the compositional zoning of the Mount Mazama magma chamber.
Photo unmodified. August 18, 2011.
FlashEarth location.
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