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| | Volcanic and Geologic Terms |
 | | Continental Drift: The theory that horizontal movement of the earth's surface causes slow, relative movements of the continents toward or away from one another. |
 | | Plate Tectonics: The theory that the earth's crust is broken into about 10 fragments (plates,) which move in relation to one another, shifting continents, forming new ocean crust, and stimulating volcanic eruptions. |
 | | Tuff Ring: A wide, low-rimmed, well-bedded accumulation of hyalo-clastic debris built around a volcanic vent located in a lake, coastal zone, marsh, or area of abundant ground water. |
| volcano.und.edu /vwdocs/glossary.html (4560 words) |
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