Across
- 3. many types of animals go extinct
- 4. fossils in which minerals are replace all of an organism
- 7. the number of years that have passed since a rock has formed
- 9. the time it takes for half of the radio active atoms to decay
- 11. animals with backbones
- 13. solid copy of the shape of an organism
- 14. lava that hardens on the surface and forms igneous rock
- 15. determines the relative ages of sedimentary rock layers
- 16. vertebrate that controls body temperature
- 17. part water life part land life
- 20. animals without backbones
- 23. a break in earth's crust
- 25. scientist who studies fossils
- 26. provide evidence of the activities of ancient organisms
- 27. balls of dust, gas, and ice that orbit the sun
Down
- 1. a widely distributed fossil in a short time
- 2. extremely thin coating of carbon on rock
- 5. preserved remains or traces of living things
- 6. record of the geological events and the evolution of the life forms as shown in the fossil record
- 8. igneous rock caused by magma
- 10. organisms that no longer exists
- 12. the particles released by elements
- 18. broken down eras
- 19. gap in the geological record
- 21. broken down eons
- 22. its age compared to the ages of rocks
- 24. hollow area of sediment in the shape of an organism