Across
- 5. are the preserved remains or traces of living things
- 7. magma cools and hardens into a mass of igneous rock called an intrusion
- 8. is a record of the geologic events and evolution of life forms as shown in fossil record
- 10. is its age compared to the ages of other rocks
- 12. lava that hardens on the surface and forms igneous rock
- 13. it no longer exists and will never again live on Earth
- 14. is a ball of dust,gas and ice that orbits the sun
Down
- 1. scientist who study fossils
- 2. of a radioactive element is the time it takes for half of the radio active atoms to decay
- 3. is the change in living things over time
- 4. these elements release particle and energy in a process
- 6. a absolute age of a rock is the number of years that have passed since the rock formed
- 9. is a gap in the geologic record
- 11. eras are subdivided into units of geologic time
- 12. geologist divide the time between precambrian time and the present into three long units of time