Editing Pillow lava (section)

==Occurrence==
They occur wherever lava is extruded underwater, such as along marine [[hotspot (geology)|hotspot]] [[volcano]] chains and the [[Divergent boundary|constructive plate boundaries]] of [[mid-ocean ridge]]s. As new oceanic crust is formed, thick sequences of pillow lavas are erupted at the [[spreading center]] fed by [[dike (geology)|dykes]] from the underlying [[magma chamber]]. Pillow lavas and the related [[sheeted dyke complex]]es form part of a classic [[ophiolite]] sequence (when a segment of oceanic crust is [[obduction|thrust over]] the [[continental crust]], thus exposing the oceanic segment above sea level).

The presence of pillow lavas in the oldest preserved volcanic sequences on the planet, the [[Isua greenstone belt|Isua]] and [[Barberton belt|Barberton]] [[greenstone belt]]s, confirms the presence of large bodies of water on the Earth's surface early in the [[Archean]] Eon. Pillow lavas are used generally to confirm subaqueous volcanism in [[metamorphism|metamorphic]] belts.

Pillow lavas are also found associated with some [[subglacial volcano]]es at an early stage of an eruption.<ref>[http://www.norvol.hi.is/html/geol/intro/introduction.pdf Geology and geodynamics of Iceland, R.G. Trønnes, Nordic volcanological Institute, University of Iceland]</ref><ref>{{cite web|url=https://www.sciencedaily.com/releases/2010/04/100426092807.htm |title=Scientists Study 'Glaciovolcanoes,' Mountains of Fire and Ice, in Iceland, British Columbia, US ScienceDaily, Apr. 23, 2010 |publisher=Sciencedaily.com |access-date=2014-03-10}}</ref>