Lava
Lavaismagma,hot molten rock thatflowsthrough holes in theEarth's crustand onto thesurface.Likemagma,lava can be eitherviscous(~thick) or fluid (~thin).[1]Blocky lava is so thick and slow that it barely moves along the ground. Other types of lava, likepahoehoe,aa,andpillow lava,are thinner and flow faster.[1]Lava sometimes sets things on fire. Sometimes it even destroys towns.
Types of lava[change|change source]
Blocky lava[change|change source]
Blocky lavais cool, stiff lava that cannot travel far from where it was erupted. Blocky lava usuallyoozesout from avolcanoonly after an explosion has let out lots of the gas pressure from the place where there is magma. Blocky lava makesjumbledpiles of sharp chunks.
Pahoehoe[change|change source]
Pronouncedpah HOY HOY,[1]pahoehoegets its name from the Hawaiian word for "ropy" because its surface looks likecoilsof rope. Pahoehoe lava flows slowly, like wax dripping down from acandle,making a glassy surface with round wrinkles.[1]
Aa[change|change source]
Aais aHawaiianword that is pronouncedAH-AH.This lava that has a sharp,jaggedsurface.[1]This stiff lava pours out quickly and makes a crust that breaks easily. The crust is torn into sharp pieces as the hot lava underneath still moves.
Pillow lava[change|change source]
Pillow lava is made when lava erupts underwater. It makes round lumps that are the size and shape ofpillows.[1]Pillow lava has a round shape because the lava cools very quickly when it touches water.[1]
They occur wherevermaficor intermediate lavas push out under water. This happens along marinehotspotvolcanochains and theconstructive plate boundariesofmid-ocean ridges.Pillow lavas occur in the oldest preserved volcanic sequences on earth, theIsuaandBarbertongreenstone belts.This shows that large bodies of water were on the Earth's surface early in theArchaean.Pillow lavas are used generally to show volcanism occurred underwater inmetamorphicbelts. Pillow lavas are also found wherevolcanoeswere undericeearly before an eruption.[2][3]
Lava tube[change|change source]
A lava tube is a natural channel formed in flowing lava. The lava continues flowing under the tube's upper surface. Later, when the lava is cooled and solid, the tube remains as a feature in thelandscape.
Gallery[change|change source]
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Strombolieruption. The yellow/reddish things in the picture are lava. -
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When lava cools down it looks like this. Those are drips of lava which have become cold again
References[change|change source]
- ↑1.01.11.21.31.41.51.6Earth Science.Holt, Rinehart and Winston, Austin, Texas. 2001.ISBN0-03-055667-8.
- ↑"Introduction to geology and geodynamics of Iceland, R.G. Trønnes, Nordic volcanological Institute, University of Iceland"(PDF).Archived fromthe original(PDF)on 2010-08-14.Retrieved2012-07-31.
- ↑Scientists Study 'Glaciovolcanoes,' mountains of fire and ice, in Iceland, British Columbia, US ScienceDaily, Apr. 23, 2010
Other websites[change|change source]
