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Table T2. Classification of volcanic lithologies. (See table notes.)

Tephras Volcaniclastic deposits Epiclastic deposits
>64 mm Pyroclastic breccia Volcaniclastic breccia/conglomerate Breccia/Conglomerate
2–64 mm Lapilistone/Lapili tuff Volcaniclastic gravel Gravel
64 µm–2 mm Coarse ash/tuff Volcaniclastic sandstone Sandstone
2–64 µm Fine ash/tuff Volcaniclastic siltstone Siltstone
<2 µm Volcanic dust Volcaniclastic volcanic dust Claystone
Amount of pyroclasts ≥75% <75% to >25% ≤25%

Notes: Modified after Fisher and Schmincke (1984). If >25% of volcaniclasts are vitric pyroclasts, then material is tuffaceous.

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