It looks in hand sample identical to the ash and lapilli deposited around the summit dome. This would indicate at least one of the recent phreatic eruptions was of enough force to deposit an ashfall mantle outside of the caldera. It is of an earlier timing than the deposit observed at the summit that is sitting on new snow, as this one is only appearing as the firn melts away. It must be within the last year though as this fine ash would not stay in stratigraphic section as the snow melts and it is carried away by wind and water. Angie will be addressing the latter question as soon as we get out of the field and can get samples prepared.
Text summary is below.
The small summit caldera of Makushin is roughly 3 km in diameter. A crater in the top of the dome is filled with a lime-green lake about 40 meters across, visible only when steam clouds briefly swirl away from the crater. Surrounding the rim of the dome's crater are large pieces of older lavas and muddy sediment with numerous marble-sized accretionary lapilli, which were explosively ejected sometime within the last year. Northwest of the main dome a smaller crater in the snow also emits sulfurous fumes from several fumaroles. This, and another dry crater to the northeast, are each about one-half kilometer in diameter.