pillow lava

noun Geology.

lava in the form of an agglomeration of rounded, pillow-shaped masses, the result of subaqueous or subglacial volcanic eruption.

Origin of pillow lava

First recorded in 1900–05

British Dictionary definitions for pillow lava

pillow lava


lava that has solidified under water, having a characteristic structure comprising a series of close-fitting pillow-shaped masses

Scientific definitions for pillow lava

pillow lava
[ pĭlō ]

Lava that forms from an underwater eruption and is characterized by pillow-shaped masses. Pillow lava forms when hot lava is suddenly exposed to cold water, forming a sacklike membrane that is filled with additional cooling and solidifying lava. The outer membrane is usually finer grained than the inner lava.