Plate tectonics

1. a narrow hole that is dug into the ground.
4. The opening at the Earth's surface through which volcanic materials (lava, tephra, and gases) erupt. Vents can be at a volcano's summit or on its slopes; they can be circular (craters) or linear (fissures).
7. Molten rock containing liquids, crystals, and dissolved gases that forms within the upper part of the Earth's mantle and crust. When erupted onto the Earth's surface, it is called lava.
9. A written record of an earthquake, recorded by a seismograph.
14. Used loosely as a collective term for all consolidated pyroclastic rocks.
15. One of the huge sections which make up the Earth's crust.
16. That point within the Earth from which originates the first motion of an earthquake and its elastic waves.
17. To bounce back from a surface.
18. To bend or change direction.
19. The term used for magma once it has erupted onto the Earth's surface.
20. the part of the earth that surrounds the central core.

2. the round hole at the top of a volcano, or a hole in the ground similar to this.
3. the solid outer layer of the earth.
5. A steep-sided mount that forms when very viscous lava is extruded from a volcanic vent.
6. Term used to describe volcanic rock or magma composed chiefly of dark-colored, iron- and magnesium-rich minerals.
8. the distance between the top and the bottom of a wave.
10. the thin, almost liquid, layer under the hard rock that forms the outer layer of the earth.
11. a linear zone where the Earth's crust.
12. forms when blobs of gas-charged lava are thrown into the air during an eruption and cool in flight, falling as dark volcanic rockcontaining cavities created by trapped gas bubbles.
13. Pertaining to igneous rock bodies that form at great depth.