Changes

[[Image:Lava.jpg|thumb|300px|Lava moves across the ground as a [[pahoehoe]] flow, Kilauea Volcano, Hawai`i]]  

[[Image:Lava.jpg|thumb|300px|Lava moves across the ground as a [[pahoehoe]] flow, Kilauea Volcano, Hawai`i]]  

'''Lava''' is the term for [[magma]] from the [[Earth]]'s [[mantle]] when it erupts onto the Earth's surface. [[Geologists]] also use the word to describe the solidified deposits of lava flows and fragments hurled into the air by explosive eruptions (for example, [[lava bombs]] or blocks). Lavas differ in chemical composition, but most forms of lava average 3000-4000 degrees [[Fahrenheit]].  Lavas are classified into the following categories based on their chemical composition: [[Basalt]] ([[Hawaii]]an [[volcano|volcanoes]]), [[Andesite]] ([[Andes]] Mountains), [[Dacite]] ([[Mt. St. Helens]]), or [[Rhyolite]] ([[Yellowstone National Park|Yellowstone]] [[caldera]]).

'''Lava''' is the term for [[magma]] from the [[Earth]]'s [[mantle]] when it erupts onto the Earth's surface. Lava differs from magma in that it contains less dissolved gases, due to the decreased pressure at the surface. [[Geologists]] also use the word to describe the solidified deposits of lava flows and fragments hurled into the air by explosive eruptions (for example, [[lava bombs]] or blocks).

 

Lavas differ in chemical composition, but most forms of lava average 3000-4000 degrees [[Fahrenheit]].  Lavas are classified into the following categories based on their chemical composition: [[Basalt]] ([[Hawaii]]an [[volcano|volcanoes]]), [[Andesite]] ([[Andes]] Mountains), [[Dacite]] ([[Mt. St. Helens]]), or [[Rhyolite]] ([[Yellowstone National Park|Yellowstone]] [[caldera]]). Lava flow is classified into two types: [[pahoehoe]], which has low viscosity and moves quickly in roping patterns, and [[aa]], which moves slowly by crumbling over itself.

 

One can generally get as close as 1.5 metres to a lava flow before his or her clothes ignite.

[[category:Igneous rocks]]

[[category:Igneous rocks]]