Lapilli
Lapilli are fragments of magma, accessory, or accidental material
between 2 to 64 mm in maximum dimension that are ejected from a volcano.
Tephra derived directly from erupting magma is termed
juvenile.
Accretionary lapilli are spheroidal, concentrically layered
pellets of ash. In 1790, an explosive eruption occurred at the summit of
Kilauea. The eruption was driven by gas leaving the magma and from steam
explosions. Rain passed through the ash cloud, and particles adhered
together to form accretionary lapilli. The accretionary lapilli is this
photo form a thin layer in the Kau Desert on the trail to Mauna Iki.
Photo by Steve Mattox, July, 1995.
The footprints of Hawaiian warriors are preserved in a layer of ash and
accretionary lapilli in the Kau Desert southwest of the summit of
Kilauea. Photo by Steve Mattox, July 1995.
