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[[Image:Mud_volcano.jpg|thumb|300px|Mud volcano in the Norris Geyser Basin, Yellowstone National Park, Wyoming. The mud volcano is about 40 cm tall.]]A '''mud volcano''' is a small volcano-shaped cone of mud and clay, usually less than 1-2 m tall. These small mud volcanoes are built by a mixture of hot water and fine sediment (mud and clay) that either pours gently from a vent in the ground like a fluid lava flow or  is ejected into the air like a lava fountain by escaping volcanic gas and boiling water. The fine mud and clay typically originates from solid rock--volcanic gases and heat escaping from magma deep below turn groundwater into a hot acidic mixture that chemically changes the rock into mud- and clay-sized fragments.<ref>http://volcanoes.usgs.gov/Products/Pglossary/MudVolcano.html</ref>

[[Image:Mud_volcano.jpg|thumb|300px|Mud volcano in the Norris Geyser Basin, Yellowstone National Park, Wyoming. The mud volcano is about 40 cm tall.]]A '''mud volcano''' is a small [[volcano]]-shaped cone of mud and clay, usually less than 1-2 m tall. These small mud volcanoes are built by a mixture of hot water and fine sediment (mud and clay) that either pours gently from a vent in the ground like a fluid lava flow or  is ejected into the air like a lava fountain by escaping volcanic gas and boiling water. The fine mud and clay typically originates from solid rock--volcanic gases and heat escaping from magma deep below turn groundwater into a hot acidic mixture that chemically changes the rock into mud- and clay-sized fragments.<ref>http://volcanoes.usgs.gov/Products/Pglossary/MudVolcano.html</ref>

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