1. Geologic Time Scale

2. What is the geologic time scale?
Time-line of Earth’s history
Breaks down Earth’s history into units of time

3. Eras are the largest unit of time. Precambrian Paleozoic Mesozoic
Cenozoic
Eras are divided into smaller parts called periods.
Periods are then divided into even smaller parts called epochs.

4. Era
Period
Epoch

5. Precambrian Era Earliest span of time in Earth’s history.
No life for a long time and then very simple life appears.
Early life influenced by volcanoes and mountain building

6. Precambrian (cont.) Oldest rock 4 bya Single-celled organisms 3.6 bya
Canadian Shield formed 3.6 bya
(bya= billion years ago)

7. Paleozoic Era Took place after Precambrian Era
“Age of Fishes”: living organisms only existed in the seas
Early invertebrates and amphibians (first animals to live on land)
Tropical climates allowed growth of new species
Forests of trees developed

8. Paleozoic Era (cont.)
Formation of Appalachian Mountains in eastern Canada
Mass extinction at end of era when 80% of marine invertebrates disappeared
Cause of extinction is not clear, but may be related to formation of Pangaea

9. Mesozoic Era Beginning of the break up of Pangaea
North American plate collides with Pacific Plate: formation of Coast Range, then Rocky Mountains
“Age of Reptiles”
Reptiles, small mammals, dinosaurs and small birds

10. Mesozoic Era (cont.) Warm climate in Canada
Creation of coal, oil and gas in western Canada
Era ended with mass extinction by asteroid or climate change
50% of all plant and animal species (including dinosaurs) became extinct.

11. Cenozoic Era The Era we are currently in!!! “Age of Mammals”
Mammals, flowering plants
Canada experienced an Ice Age with four periods of glacial activity
First humans

12. Cenozoic Era
We still have much diversity but could there be a mass extinction to come???

13. Formation of Canada
Let’s draw…