Superficially similar to the scoria fall deposit in Slide 20, this 2 m thick plinian deposit also consists of well sorted clasts 1-3 cm in diameter. These are of rhyodacitic composition. Unlike the scoria fall deposit which is of limited areal extent, this plinian deposit mantles an area of many hundreds of square kilometers and was erupted from a much higher eruption column, possibly reaching an altitude of 30 km. The pumice layer shows slight evidence of internal layering or shower bedding. It is overlain by several other fall units of different composition, which were apparently erupted without a major erosional interval. It is not known when the plinian deposit was erupted. (Fig. 9.22).

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