Plate tectonics

2. Underwater mountain range formed when two plates move apart
6. any of the many processes (such as eruptions and lava flows) in which gas, lava, and ash are pushed out on the surface of Earth
11. when two plates are moving apart from each other
13. something we observe to be similar over and over again
16. when two plates slide next to each other
17. an object, diagram, or computer program that helps us understand something by making it simpler or easier to see
19. The person who invented the theory of plate tectonics
21. a set of interacting parts forming a complex whole

1. a feature that forms on the surface of a planet, such as a mountain, channel, or sand
3. There are 12 on earth
4. The name of the puzzle
5. hot liquid rock on the surface of Earth
7. Earth’s outermost layer of hard, solid rock that is underneath the soil, vegetation, and water
8. the layer of soft, solid rock underneath Earth's plates
9. the layer under the land and ocean
10. these often happen at convergent boundaries when two plates colide
12. these happen often at a divergent boundary when the mantle is coming up between two plates
14. our teacher
15. When two plates move together and one goes under the other
18. the outside or top layer of something
20. The planet we live on