| lava in the form of an agglomeration of rounded, pillow-shaped masses, the result of subaqueous or subglacial volcanic eruption. |
| pillow lava n. Lava that forms from an underwater eruption and is characterized by pillow-shaped masses. |
pillow lava  (pĭl'ō) Pronunciation Key
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. |