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Pillow lava is the lava structure typically formed when lava emerges from an underwater volcanic vent or subglacial volcano or a lava flow enters the ocean. The viscous lava gains a solid crust on contact with the water, and this crust cracks and oozes additional large blobs or "pillows" as more lava emerges from the advancing flow.
The magma, which is brought to the surface through fissures or volcanic eruptions, rapidly solidifies. Hence such rocks are fine-grained or even glassy. Basalt is the most common extrusive igneous rock [9] and forms lava flows, lava sheets and lava plateaus.
The thickness of a basalt lava, particularly on a low slope, may be much greater than the thickness of the moving lava flow at any one time, because basalt lavas may "inflate" by supply of lava beneath a solidified crust. [31] Most basalt lavas are of ʻAʻā or pāhoehoe types, rather than block lavas.
The terms lava stone and lava rock are more used by marketers than geologists, who would likely say "volcanic rock" (because lava is a molten liquid and rock is solid). "Lava stone" may describe anything from a friable silicic pumice to solid mafic flow basalt, and is sometimes used to describe rocks that were never lava, but look as if they ...
The lava flowing from stratovolcanoes typically cools and solidifies before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high to intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less viscous mafic magma. [4]
Pele's tears (closest Hawaiian translation: "nā waimaka o Pele") are small pieces of solidified lava drops formed when airborne particles of molten material fuse into tearlike drops of volcanic glass. Pele's tears are jet black in color and are often found on one end of a strand of Pele's hair.
The ridges and patterns on top of the lava field show the direction of the lava channels and the often active lava tubes that may be underneath the solidified "crust." [1] It can also reveal whether the lava flow can be classified as pāhoehoe or 'a'ā. The two main types of lava field structures are defined as sheet flow lava and pillow lava ...
A lava spine (or lava spire) is a vertical growth of solid lava that is forced from a volcanic vent. A lava spine can either be formed by viscous lava slowly being pushed out of the vent, or by magma that has solidified within the vent before being pushed out.