Volcanoes

6. plates The dozen or so plates that make up the surface of the Earth. Their motion is studied in the field of plate tectonics.
7. distributed or occurring at widely spaced and usually irregular intervals
11. a large kettle or boiler.
13. to follow the footprints, track, or traces of
16. fizzy
17. a layer of material, naturally or artificially formed, often one of a number of parallel layers one upon another
19. an opening, as in a wall, serving as an outlet for air, smoke, fumes, or the like
20. nourishing substance
21. a vault, having a circular plan and usually in the form of a portion of a sphere, so constructed as to exert an equal thrust in all directions
22. the portion of the earth, about 1,800 miles (2,900 km) thick, between the crust and the core

1. the highest point or part, as of a hill, a line of travel, or any object; top; apex
2. a broad piece of armor, varying widely in form and size, carried apart from the body, usually on the left arm, as a defense against swords, lances, arrows, etc
3. the brown, hard outer portion or surface of a loaf or slice of bread
4. having an almost vertical slope or pitch, or a relatively high gradient, as a hill, an ascent, stairs, etc
5. a door, gate, or entrance, especially one of imposing appearance, as to a palace.
8. the central, innermost, or most essential part of anything
9. to send forth (liquid, light, heat, sound, particles, etc.); discharge.
10. liquefied by heat; in a state of fusion
12. bearing, producing, or capable of producing vegetation, crops, etc., abundantly; prolific
14. to break, break open, or fly apart with sudden violence
15. burning or scorching
18. to alter the environment of (a celestial body) in order to make capable of supporting terrestrial life forms