Complete the crossword puzzle.

| Across | Down |
| 4. to crash into | 1. a layer of molten rock beneath Earth's crust |
| 6. the length of time that something lasts | 2. a border or an edge |
| 7. a tool that records movements in Earth's crust | 3. large sections of Earth's crust |
| 8. a break in Earth's crust where blocks of rock are moving in different directions | 5. to act on one another |