Tephra is a general term for fragments of volcanic rock and lava that are
blasted into the air by explosions or carried upward by hot gases in eruption
columns or lava fountains. Tephra includes large, dense blocks and
bombs, and small, light rock debris such as scoria, pumice,
reticulite, and ash.
Left: A fountain of hot lava and tephra erupts from a crater in Hawaii's Kilauea East Rift in 1983.