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[[Image:Fissure.jpg|thumb|300px|Eruptive fissure on southeast rim of Kilauea caldera, Hawaii.]]

[[Image:Fissure.jpg|thumb|300px|Eruptive fissure on southeast rim of Kilauea caldera, Hawaii.]]

In geology, a '''fissure''' is a fracture or crack in rock along which there is a distinct separation; fissures are often filled with mineral-bearing materials. On volcanoes, a fissure is an elongate fracture or crack at the surface from which lava erupts. Fissure eruptions typically dwindle to a central vent after a period of hours or days. Occasionally, lava will flow back into the ground by pouring into a crack or an open eruptive fissure, a process called drain back; sometimes lava will flow back into the same fissure from which it erupted.<ref>http://volcanoes.usgs.gov/Products/Pglossary/fissure.html</ref>

In [[geology]], a '''fissure''' is a fracture or crack in rock along which there is a distinct separation; fissures are often filled with mineral-bearing materials. On [[volcano|volcanoes]], a fissure is an elongate fracture or crack at the surface from which lava erupts. Fissure eruptions typically dwindle to a central vent after a period of hours or days. Occasionally, lava will flow back into the ground by pouring into a crack or an open eruptive fissure, a process called drain back; sometimes lava will flow back into the same fissure from which it erupted.<ref>http://volcanoes.usgs.gov/Products/Pglossary/fissure.html</ref>

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==References==