Upper Pumice is 3-20cm thick and dark yellow-brown, a mixture of brown-beige pumice and dark gray-black scoria (42 wt% and 23 wt% of layer, respectively) and an abundance of non-vitric lithics (32 wt% of layer). Overall the PU lapilli are poorly sorted and vary in mean grain size (6-14mm) with the layer. Scoriaceous clasts are larger tha pumiceous clasts and lithic fragments (mean dia ~5mm and ~3mm, respectively). Scoriaceous bombs up to 10cm in the long dimension occur up to 10km from summit.
Stratigraphy, distribution, and evidence for mafic triggering of the ca. 8.5 ka Driftwood Pumice eruption, Makushin Volcano, Alaska, U.S.A.
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