Across
- 4. spreading Harry Hess discovered what
- 6. the hottest layer on earth
- 7. move away from each other
- 9. drift Alfred Wegner discovered what
Down
- 1. places where plates slide sideways
- 2. the thinnest layer on the earth
- 3. two or more lithospheric plates collide
- 5. occurs as tectonic plates are pushed together
- 8. a fracture or a crack between
- 10. plates are gigantic pieces of the Earth's crust