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Volcano Term Definitions
The Spanish word for cauldron, a basin-shaped volcanic depression; by definition, at least a mile in diameter. Such large depressions are typically formed by the subsidence of volcanoes. Crater Lake occupies the best-known caldera in the Cascades.
A volcano constructed by the ejection of debris and lava flows from a central point, forming a more or less symmetrical volcano.
A volcanic cone built entirely of loose fragmented material (pyroclastics.)
A steep-walled horseshoe-shaped recess high on a mountain that is formed by glacial erosion.
The breaking of a mineral along crystallographic planes, that reflects a crystal structure.
A steep volcanic cone built by both lava flows and pyroclastic eruptions.
Solid, outer layers of the earth, including the rocks of the continents.
The theory that horizontal movement of the earth's surface causes slow, relative movements of the continents toward or away from one another.
The rock intruded by and surrounding an igneous intrusion.
A steep-sided, usually circular depression formed by either explosion or collapse at a volcanic vent.
A part of the earth's crust that has attained stability and has been little deformed for a prolonged period.
A row of coalescing lava fountains along a fissure; a typical feature of a Hawaiian-type eruption