Index fossils
- 1. Relative Age Age of a rock compared to the ages of other rocks
- 2. Absolute Age Number of years since the rock formed
- 3. Law of Superposition Scientists use to determine RELATIVE age of a rock Youngest layer is always located on the top, oldest layer always located on the bottom
- 4. Law of Superposition Activity Rock layers T and C are the oldest Each card must contain one common letter Place cards in order as they might appear in a canyon
- 5. How do you know X is older than M? Explain why D in the rock layer represented by DM is the same age as M Explain why D in the rock layer OXD is older than D in the rock layer DM TC CGA AU UBN BN NO OXD DM
- 6. Index Fossils Fossils of widely distributed organisms that lived during only one short time period
- 9. How has the environment changed?
- 10. Determining Relative Age using fossil evidence Sequence the cards according to relative age Keep in mind that extinction is forever Layer M is the oldest
- 11. How’d you do? What clues did you use to help you determine the rock sequence? Are any of the fossils good index fossils? Why?
- 12. Reflection page 42 If humans were to suddenly become extinct, do you think that we would be a good index fossil? Why or why not?