Across
- 3. the minerals in groundwater replace the minerals that make up the bodily remains after the water completely dissolves the original hard parts of the organism
- 5. a process of fossilization in which mineral deposits form internal casts of organisms.
- 6. determined by using radiometric dating.
- 7. no longer existing
- 10. sequence of layers of sedimentary rock
- 12. 252-66 million years ago
- 13. where only a thin carbon layer is left on a piece of shale
- 15. DNA found in tar and/or ice
Down
- 1. occurs when the organic matter is completely replaced by minerals and the fossil is turned to stone
- 2. the age of a rock layer (or the fossils it contains) compared to other layers
- 4. beginning about 66 million years ago and extending to the present
- 8. a fossil that is useful for dating and correlating the strata in which it is found.
- 9. 541 million years ago
- 11. a fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.
- 14. things preserved in "amber"