Grade 8 - Exam Review Unit 3

3. Earth's thin outer shell. It is made primarily of low-density materials called silicates.
4. The formation of the solar system was similar to the differentiation of Earth into layers because in both processes the densest materials moved to the _____.
7. Cycling of material due to differences in density.
8. The point of Earth's surface directly above the focus.
12. Type of stress associated with transform boundaries.
13. Type of boundary where plates slide past one another.
14. The process of _____ decay generated heat during Earth's formation and is still a source of heat in Earth's interior.
15. A break in Earth's crust along which blocks of rock move.
16. A _____ boundary forms when two tectonic plates move away from each other.
20. Type of stress associated with convergent boundaries.
21. Type of stress associated with divergent boundaries.
22. the process by which one tectonic plate is pulled beneath another plate.

1. _____ tectonics is the scientific theory explaining that the lithosphere is divided into moving slabs.
2. A block of lithosphere that consists of the crust and the rigid outermost part of the mantle is a _____ plate.
3. Type of boundary where plates move toward each other.
5. A change of the magnetic poles is a magnetic ___.
6. The hypothesis that today's continents were once part of a single landmass, or supercontinent, called Pangaea is _____ drift.
9. Ground movements that occur when blocks of rock in Earth move suddenly and release energy.
10. The process by which new seafloor forms is seafloor ____.
11. ___ is caused by stress and is the bending, tilting, and breaking of rock.
17. At the center of Earth. Contains very dense elements, mainly iron and a small amount of nickel.
18. A place within Earth along which the first motion of an earthquake occurs.
19. The compositional layer below the crust. It contains silicate materials, but has more dense elements as well.