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Volcano Term Definitions
A period of time in the Paleozoic Era that covered the time span between 400 and 345 million years.
A breccia filled volcanic pipe that was formed by a gaseous explosion.
A steep-sided mass of viscous (doughy) lava extruded from a volcanic vent (often circular in plane view) and spiny, rounded, or flat on top. Its surface is often rough and blocky as a result of fragmentation of the cooler, outer crust during growth of the dome.
The area of land drained by a river system.