Pillow lava

Pillow lava pillow lava or ( This term was coined in 1890 by John Walter Gregory ) is under water solidified lava in cushion -like form and is therefore regarded as a sure sign of subaqueous volcanism. She is a frequent occurrence along the mid-ocean ridges, and therefore an essential part of ophiolite - oceanic crust that was pushed onto continental crust.

Your glazed consistency owes the solidified lava to the extremely rapid cooling of the hot molten rock upon contact with water, a medium that can absorb large amounts of heat. A viscous plastic mass of rock forms at the glass surface rapidly cooled. In the interior of the pad lava cools considerably slower, so that it comes to form a crystalline mass. Thereby generally radially disposed gas bubble rings arising just below the crust, since on leaving the lava rock undergoes a massive pressure relief and therefore leads to degassing of the melt. Flowing Lava to another, tearing the envelope on at one point and another pillow arise. The individual cushions are 0.2 to 1 m tall and form on the ocean floor up to 1 km thick layers. In the spandrels between the Lavakissen there is volcanic tuff, chipped glassy Lavasplitter, and seafloor sediment.