Across
- 5. a large division of geologic time
- 7. comparing the age of rock layers
- 8. a radioactive form of the element carbon
- 9. fossils used to compare the ages of rocks
- 11. magma being pushed into cracks within Earth
Down
- 1. when ice sheets cover large areas of land
- 2. the exact age
- 3. any preserved traces of life
- 4. the ancient supercontinent
- 6. older rock layers are on the bottom
- 10. a break in the rock of earths crust