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intraplate volcanism: HOT SPOTS AND MANTLE PLUMES. Although most volcanic rocks are generated at plate boundaries, there are a few exceptionally active sites of volcanism within the plate interiors. These intraplate regions of voluminous volcanism are called hotspots.
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ring of fire: The Ring of Fire is an area where a large number of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean.
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lava: hot molten or semifluid rock erupted from a volcano or fissure, or solid rock resulting from cooling of this.
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magma: hot fluid or semifluid material below or within the earth's crust from which lava and other igneous rock is formed by cooling.
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viscosity: the state of being thick, sticky, and semifluid in consistency, due to internal friction.
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silica content: the dioxide form of silicon, SiO 2 , occurring especially as quartz sand, flint, and agate: used usually in the form of its prepared white powder chiefly in the manufacture of glass, water glass, ceramics, and abrasives.