pillow lava

noun

, Geology.

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

pillow lava

noun

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

pillow lava

/ pĭl′ō /

1. 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.

Word History and Origins

Origin of pillow lava¹

First recorded in 1900–05