Fossils and Geologic Time

4. Fossils that help scientists determine the age of rocks or fossils because they are easily recognizable, abundant, there is a wide geographic distribution of them, and they lived in a short period of geographic time.
6. This states that the newest rock layers are on top and the oldest rock layers are on the bottom unless something happens.
8. Era of geographic time that means the age of medieval life.
10. no longer living or died out completely
12. A type of petrification that happens when fossils are preserved instead of replaced.
13. Fossils that are created when all substances of the living thing decay except for carbon which leaves a carbon film on sedimentary rock.
15. Finding what the probable age of a fossil is by where they are located in the rock strata.

1. Fossils that are created when an animal or plant leaves behind indirect evidence such as footprints, tracks, or burrows.
2. Fossils created when an organic material gets replaced by stone.
3. Fossils that are created when an animal gets trapped in tar or ice and the whole body can be preserved.
5. An era of geographic time that is the age of ancient life.
7. A type of petrification that happens when the fossil is replaced with rocks or minerals.
9. A type of fossil that is formed when a sticky substance captures insects and then hardens to preserve them.
11. Era of geographic time that means the age of recent life
14. The most accurate form of dating fossils that is done by determining the half-life of the fossil.