Editing Volcano (section)

===Tephra===
{{main|Tephra}}

[[File:Tuff shards.jpg|thumb|right|Light-microscope image of [[tuff]] as seen in [[thin section]] (long dimension is several mm): the curved shapes of altered glass shards (ash fragments) are well preserved, although the glass is partly altered. The shapes were formed around bubbles of expanding, water-rich gas.]]
Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases [[Extrusion|when it flows to the surface]]. These violent explosions produce particles of material that can then fly from the volcano. Solid particles smaller than 2&nbsp;mm in diameter ([[sand|sand-sized]] or smaller) are called volcanic ash.<ref name="EB1911">{{EB1911|wstitle=Tuff|inline=1}}</ref><ref name="schmidt-1981">{{cite journal|last1=Schmidt|first1=R.|title=Descriptive nomenclature and classification of pyroclastic deposits and fragments: recommendations of the IUGS Subcommission on the Systematics of Igneous Rocks|journal=Geology|volume=9|year=1981|issue=2|pages=41–43|doi=10.1007/BF01822152|bibcode=1981GeoRu..70..794S|s2cid=128375559|url=https://scholar.google.com/scholar_url?url=https://idp.springer.com/authorize/casa%3Fredirect_uri%3Dhttps://link.springer.com/content/pdf/10.1007/BF01822152.pdf%26casa_token%3DEeQQK-27EzMAAAAA:NxHAz8w30oOg24-BcWvJPAgMBjRc419lq-7Jz-6VV0-ma9Mv2wxmt4JqRZoPtxQvU501TeyvkUDq1fmmJw&hl=en&sa=T&oi=gsb-gga&ct=res&cd=0&d=227239637425471251&ei=PBhxX4PbJrXCywTH6bfYBg&scisig=AAGBfm2m9NmvueO9pSpn98cYOcYAhzm0nw|access-date=September 27, 2020|url-access=subscription}}</ref>

Tephra and other [[volcaniclastics]] (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism.{{sfn|Fisher|Schmincke|1984|p=89}}