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Across 1. The subterranean cavity containing the gas-rich liquid magma which feeds a volcano. 5. Movement in a fluid caused by uneven heat. 7. Undersea mountian range with a steep, narrow valley along its center. 9. The Point on the earth's surface directly above the point where an earthquake or other underground explosion originate. 11. Movement of the ocean floor away from either side of a mid-ocean ridge. 15. Mass of lava, created by many individual flows, that has built a dome-shaped pile of lava. 16. Solid outer layers of the earth, including the rocks of the continents. 17. A vent in the surface of the earth through which magma and associated gases and ash erupt. 19. A submarine volcano. 22. Elongated fractures or cracks on the slopes of a volcano. 23. Transfer of heat through the movement of a fluid material. 27. The theory that horizontal movement of the earth's surface causes slow, relative movements of the continents toward or away from one another. 28. The middle layer of the atmosphere. 29. System of undersea mountain ranges that wind around the earth. 30. The zone of convergence of two tectonic plates, one of which usually overrides the other. 34. A steep-sided mass of viscios (doughy) lava extruded from a volcanic vent (often circular in plane view) and spiny, rounded, or flat on top. 35. Topographical depressions of the sea floor. 38. Deep valley in the ocean floor that forms along a subduction zone. 44. An inactive volcano which may erupt again. 46. The regions of mountain-building earthquakes and volcanoes which surround the Pacific Ocean. 47. A crack or fracture in the earths surface. 48. Fine particles of pulverized rock blown from an explosion vent. 51. A numerical expression of the amount of energy relesed by an earthquake, determined by measuring earthquake wave on standardized recording instruments (seismographs.) 52. The rigid crust and upermost mantle of the earth. Stronger than the underlying asthenosphere. 55. Molten rock beneth the surface of the earth. 56. Earth quake waves that move up and down as the wave itself moves. 57. Single landmass thought to have been the origin of all continent.

Down 2. Border formed by the direct collision of two lithospheric plates. 3. The zone of the earth below the crust and above the core. 4. The opening at the earth's surface through which volcanic materials issue forth. 6. The shell within the earth, some tens of kilometers below the surface and of undefined thickness, which is a shell of weakness where plastic movments take place to permit pressure adjusments. 8. The innermost part of the earth. 10. The layer of the atmosphere we live in. 12. The buffer between the earth and the sun. 13. The 10 major pieces of the broken lithosphere. 14. Lateral flowage of a turbulant mixture of hot gases and unsorted pyroclastic material (volcanic fragments, crystals, ash, pumice, and glass shards) that can move at high speed. 15. An outpouring of lava onto the land surface from a vent or fissure. 18. The uppermost part of the earth. 20. The layer touching outer space. 21. The theory that the earth's crust is broken into and about 10 fragmentswhich move in relation to one another, shifting continents, forming new ocean crust, and stimulating volcanic eruptions. 24. The angle between the slope of a volcano and some reference. 25. A volcano that is erupting. Also, a volcano that is not presently erupting, but that has erupted within historical time and is considered likely to do so in the future. 26. Boundary formed by two lithospheric plates that are moving apart. 31. A major submarine ocean range 32. A gentle sloping volcano in the shape of a flattened dome and built almost exclusively of lava flows. 33. An instrument that records seismic waves. 35. The earth's crust where it underlies oceans. 36. The ocianic ridges formed where tectonic plates are seperating and a new crust is being created. 37. The second layer of the atmosphere. 39. A volcanic cone built entirely of loose fragmented material. 40. Pertaining to fragmented (clastic) rock material formed by a volcanic explosion or ejected from a volcanic vemt. 41. The process by which solid liquid and gaseous materials are ejected into the earths atmosphere ans onto the earth's surface by volcanic activity. 42. The midle area of the earth. 43. The layer below the exosphere. 45. A steep-sided, usually circular depression formed by either explosion or collapse at a volcanic vent. 46. Steep, narrow valley formed as lithospheric plates seperate. 49. The Spanish word for cauldron, a basin-shaped volcanic depression. 50. A flow of water-saturated earth material possessing a high degree of fluidity during movement. 53. A torrential flow of water-saturated volcanic debris down the slope of a volcano in response to gravity. A type of mudflow. 54. Magma which has reached the surface through a volcanic eruption.