1. Geologic Time

2. Separation = Change. Correlate geologic events, environmental changes, and changes among life forms

3. The Geologic Time Scale Record of Earth’s history Names of the time periods don’t change but their boundaries are always being changed.

4. Scale is cut into different sections: 1)Eon – longest time unit on the scale  Hadean (oldest)  Archean  Proterozoic  Phanerozoic (youngest)

6. 2)Era – next longest span of time Defined by the different life forms that are found in the rocks.  Precambrian (oldest)  Paleozoic  Mesozoic  Cenozoic (youngest)

8. -Precambrian Era – microscopic life -Paleozoic Era – Age of Trilobites -Mesozoic Era – Age of Reptiles -Cenozoic Era – Age of Mammals

9. 3)Periods – defined by the life forms that were abundant or became extinct during the time in which the rock was deposited.

11. 4)Epochs – smaller division of geologic time.