Figure 1

Backscattered electron images of pumices with spherical and sheared bubbles (a, 83019; b, 07BOL23PD). Black portions are bubbles; grey portions are groundmass and plagioclase. White to light grey particles represent mafic minerals. The image of a also shows broken phenocrysts in the centre. Pl, Bt and Amp represent mineral phases of plagioclase, biotite and amphibole, respectively.