Volcanoes

March 21, 2006

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Mt. Saint Helens
 
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Smoking VolcanoVOLCANO VOCABULARY

Photo Glossary of Volcanic Terms from USGS. http://volcanoes.usgs.gov/Products/Pglossary/pglossary.html

This is a good index of terms about volcanoes.
http://volcano.und.edu/vwdocs/site_index.html

Volcanic and Geologic Terms from Volcano World. http://volcano.und.nodak.edu/vwdocs/glossary.html

'A'a

lava flows that have a rough rubbly surface. Photo

active volcano a volcano that is erupting, or a volcano that is not presently erupting, but that has erupted within historical time and is considered likely to do so in the future.
ash fine particles of pulverized rock blown from an explosion vent. Photo
basalt volcanic rock (or lava) that is dark in color, contains 45% to 54% silica, iron and magnesium. Photo
caldera a basin-shaped depression at least a mile in diameter in a volcano. Crater Lake is a caldera that is in the Oregon Cascades. Photo
cinder cones

a volcanic cone built entirely of loose material. Photo

crater a depression formed by either explosion or collapse at a volcanic vent. It usually has steep sides.
dormant volcano a volcano which is presently inactive but which may erupt again. Most of the major Cascade volcanoes are believed to be dormant rather than extinct.
eruption

the process by which solid, liquid, and gaseous materials are ejected into the earth's atmosphere and onto the earth's surface by volcanic activity. Eruptions can be a quiet overflow of liquid rock or a tremendously violent explosion.

extinct volcano a volcano that is not presently erupting and is not likely to do so in the future.
fissures fractures or cracks on the slopes of a volcano. Photo
geyser

hot springs that rise along cracks and erupt on the earth's surface. Surface water percolates downward through the rocks below the Earth's surface to high-temperature area. Geysers are found in regions of young volcanic activity. Old Faithful Web Cam

lava melted (molten) rock which has reached the surface of the earth through a volcanic eruption. Cooled and solidified rock is also called lava. Photo
lava flow the outpouring of lava onto the land from a vent or fissure. Photo
lava tube a tunnel formed when the surface of a lava flow cools and solidifies while the still-molten interior flows through and drains away. Photo
magma melted (molten) rock inside the earth
pahoeho Hawaiian term for lava with a smooth, billowy, or ropy surface. Photo
pillow lava

the formation of basalts that erupt underwater Photo

plate 10 fragments of the earth's crust which move in relation to one another.
Ring of Fire the regions of mountain-building earthquakes and volcanoes which surround the Pacific Ocean. Diagram
Volcanologist a person who studies volcanoes and their behavior
Volcanology the science of volcanoes
Vulcan Roman god of fire and the forge after whom volcanoes are named.
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