GEOLOGY

Detailed explanation-1: -Pillow basalt is a volcanic igneous rock that forms when lava of basaltic compositionis erupted underwater. The rapid cooling of the lava by cold water on all sides forms the pillow-shaped bodies, which can then break open and extrude more of the hot lava from inside.

Detailed explanation-2: -Pillow lava. Pillow lavas are bulbous, spherical, or tubular lobes of lava. They form during eruptions with relatively low effusion rates. Slow extrusion gives enough time for a thick crust to form on all sides of a pillow lobe, and prevents individual pillows from coalescing into a sheet.

Detailed explanation-3: -Pillow lavas are commonly of basaltic composition, although pillows formed of komatiite, picrite, boninite, basaltic andesite, andesite, dacite or even rhyolite are known. In general, the more felsic the composition, the larger the pillows, due to the increase in viscosity of the erupting lava.

Detailed explanation-4: -Pillow lavas form during subaqueous eruptions. Since almost all pillow lavas are of basaltic compositions, they are most commonly called pillow basalts.

Detailed explanation-5: -Pillow lavas typically form along submarine volcanic vents, where fresh basaltic lava tumbles over the seafloor. When molten lava oozes slowly into water, the outer–most layer quenches instantly, forming a rind of hot glass over a bulb of molten rock.