Plate Tectonics

3. Convection currents in the mantle produce a force that causes motion called _____.
4. As a slab sink, it pulls on the rest of the plate with a force called _____.
9. The theory of ____ drift suggested that continents are in constant motion on the surface of Earth.
12. The layer that is so hot that it behaves like plastic material.
15. Continents fit like pieces of a..
19. The plate tectonics move several ____ each year.
21. Wegener needed more scientific _____ to support his theory.
22. A state in which magnetized objects will orient themselves to point north is called ____ polarity.
23. A _____ plate boundary forms where two plates collide.
25. Mountain ranges in the middle of the ocean are called ____ ridges.

1. The ____ of Plate Tectonics states that Earth's surface is made of rigid slabs of rock that move with respect to each other.
2. Denser plate sinks below buoyant plate
5. Cold, rigid outermost rock layer
6. _____ on seafloor contains iron-rich minerals that are magnetic.
7. A _____ plate boundary forms where two plates separate.
8. Process by which new oceanic crust forms along a mid-ocean ridge and older oceanic crust moves away from the ridge.
10. Depth of the ocean determined by an ____ sounder.
11. Rising mantle material at mid-ocean ridges creates the potential for plates to move away from the ridge with a force called ____.
13. Wegener could not explain ___ the continents moved.
14. A state in which magnetized objects would reverse direction and orient themselves to point south is called ____ polarity.
16. _____ crust forms at mid-ocean ridges.
17. Supercontinent.
18. A _____ plate boundary forms where two plates slide past each other.
19. Circulation of material caused by differences in temperature and density
20. _____ reversal occurs when the magnetic field reverses direction.
24. ____ lava forms when lava cools rapidly since it erupts in water.