Plate tectonics

3. a linear zone where the Earth's crust.
5. A steep-sided mount that forms when very viscous lava is extruded from a volcanic vent.
6. the solid outer layer of the earth.
9. Pertaining to igneous rock bodies that form at great depth.
10. 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).
13. the thin, almost liquid, layer under the hard rock that forms the outer layer of the earth.
16. A written record of an earthquake, recorded by a seismograph.
18. The term used for magma once it has erupted onto the Earth's surface.
19. 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.
20. Used loosely as a collective term for all consolidated pyroclastic rocks.

1. 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.
4. the distance between the top and the bottom of a wave.
7. a narrow hole that is dug into the ground.
8. That point within the Earth from which originates the first motion of an earthquake and its elastic waves.
11. To bend or change direction.
12. To bounce back from a surface.
14. One of the huge sections which make up the Earth's crust.
15. Term used to describe volcanic rock or magma composed chiefly of dark-colored, iron- and magnesium-rich minerals.
17. 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.