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Volcano

Volcanic Benefits

Through geologic time, volcanic eruptions have shaped Earth's environment in many ways. The eruption of volcanoes built the continents on which we live. We owe much of the composition of our atmosphere to volcanic eruptions on the early Earth. Our oceans formed from water expelled during these same eruptions. Some of the world's richest farmland draws its fertility from minerals provided by nearby volcanoes. Volcanoes, particularly collapsed calderas, can develop geothermal systems when groundwater or rainwater seep into the volcano. Geothermally powered electric generating stations provide electricity in Iceland, Italy, and New Zealand. Volcanic processes are also responsible for precious and non-precious mineral deposits, which are formed when minerals precipitate from geothermal waters circulating in the rocks beneath and around volcanoes.

Resources

Books

De Boer, Jelle Zeilinga, and Donald T. Sanders. Volcanoes in Human History: The Far-Reaching Effects of Major Eruptions. Princeton, NJ: Princeton University Press, 2001.

Harris, Stephen. Fire Mountains of the West. Missoula: Mountain Press Publishing Co., 1988.

Periodicals

Gore, Rick. "Cascadia: Living On Fire." National Geographic (May 1998): 6-37.

Heiken, Grant. "Will Vesuvius Erupt? Three Million People Need to Know." Science (November 26, 1999): 1685

McClintock, Jack. "Under the Volcano." Discover (November 1999): 82.

Mothes, Patricia. "Waiting for the Eruption: Tungurahua Volcano, Ecuador." Geotimes (March 2000): 26-27.

Williams, A.R. "Under the Volcano: Montserrat." National Geographic (July 1997): 58-73.

Other

U.S. Forest Service. "Mount St. Helens National Volcanic Monument." January 13, 2003 [cited February 9, 2003]. <http://www.fs.fed.us/gpnf/mshnvm/>.

U.S. Geological Survey. "U.S. Geological Survey Volcano Hazards Program." January 17, 2003 [cited February 9, 2003]. <http://volcanoes.usgs.gov/>.

Clay Harris

KEY TERMS

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Ash fall: —A layer of volcanic ash that falls from an erupted ash cloud.
Cinder cone: —A small, steep-sided volcano made of pyroclastic material. A cinder cone is an accumulation of loose volcanic material that erupts as a liquid, and cools into cinders in the air, falling to the ground in a heap.
Composite volcano: —A large, steep-sided volcano made of alternating sequences of lava and pyroclastic debris. Sometimes called a stratovolcano.
Convection current: —The motion of a fluid that rises as it is heated and sinks as it cools, moving in a circular path.
Felsic: —A term applied to light-colored igneous rocks, such as rhyolite, that are rich in silica. Felsic rocks are rich in the minerals feldspar and quartz.
Fissure: —A crack through which lava erupts onto Earth's surface
Hot spot: —An upwelling of magma from beneath the earth's crust, caused by a disturbance at the boundary between the solid mantle and the liquid outer core. This upwelling is not related to the convection currents associated with oceanic ridges, although some hot spots do occur there.
Lava: —Molten rock erupted onto Earth's surface.
Mafic: —A term applied to dark-colored igneous rocks, such as basalt, that are poor in silica and contain large amounts of the iron and magnesium.
Magma: —Molten rock beneath Earth's surface.
Oceanic ridge system: —A long (40,000 mi; 64,000 km) crack in the earth's crust where new ocean crust is continuously forming, causing ocean basins to grow wider.
Pyroclastic flow: —A fast moving body of pyroclastic material from an erupting volcano. It moves as a fluid, in some cases covering thousands of square kilometers.
Pyroclastic material: —Volcanic debris formed by solidification of erupted lava in air; includes dust, ash, cinders, and blocks of rock.
Shield volcano: —A broad, low profile volcano consisting of layers of basaltic rock, typically formed in the middle of oceanic plates or on continental rifts.
Silica: —Any of the mineral forms of silicon dioxide.
Subduction zone: —A boundary between tectonic plates in which a dense oceanic plate is forced beneath a less dense continental plate.
Viscosity: —The internal friction within a fluid that makes it resist flow.
Volatile: —Readily able to form a vapor at a relatively low temperature.

Additional topics

Science EncyclopediaScience & Philosophy: Verbena Family (Verbenaceae) - Tropical Hardwoods In The Verbena Family to WelfarismVolcano - Where Volcanoes Develop, The Origin Of Magma, Types Of Volcanic Eruptions, Different Kinds Of Volcanic Structures