1. Add this unit to your Table of contents!
Geologic Time
Add this unit to your Table of contents!

2. A timeline of your education
If we made a timeline of your education, where would you fall??
What would we use as the scale?
Grade level K 12 K 1 2 3 4 5 6 7 8 9 10 11 12
4.6 billion years ago
Present day
Where would you fall on the timeline of the Earth’s history??

3. Fossils and Geologic Time
The geologic time scale organizes geologic and evolutionary events.
It is based on evidence in the fossil record and has been shaped by mass extinctions.

4. How do extinctions shape Geologic Time?
Mass extinction- A large number of species become extinct
After a mass extinction, opportunities open for new life-forms to emerge.

5. Geologic Time Scale Divisions of the Geologic Time Scale
Precambrian Era
Paleozoic Era
Mesozoic Era
Cenozoic Era

6. The Precambrian Era 4.6 billion years ago – 542 million years ago
~88% of the earth’s history

7. Major Events
Formation of the Earth’s crust from molten rock
First appearance of life --- bacteria!
First organisms could photosynthesize----
Oxygenated atmosphere
First multi-cellular organisms

8. Major Events MASS Extinction- widespread glaciation
Geologists compared the Earth to a giant snowball during this time

9. DOMINATE ORGANISMS Bacteria Multicellular organisms
Cyanobacteria and stromatolites
DOMINATE ORGANISMS
Bacteria
Multicellular organisms
Fossils found in South Australia

10. Pictures of Precambrian Era Life and Fossils

11. The Paleozoic Era
542 million years ago million years ago

12. Major Events Cambrian explosion (of life)! Primitive fishes appear
Mass EXTINCTION

13. Major Events Plants colonize land Insects and amphibians appear
ANOTHER Mass EXTINCTION

14. Major Events
Seed plants dominate land
Reptiles become dominate

15. DOMINATE ORGANISMS
Plants
Fishes
Insects
Amphibians
Reptiles

16. Pictures of Paleozoic life and fossils

17. 4.6 billion years ago – 542 million years ago
Warm-up 10/16/13
1. What years did the Precambrian Era span?
4.6 billion years ago – 542 million years ago
2. What percentage of Earth’s history does the Precambrian Era account for?
88%

18. The Mesozoic Era
251 million years ago – 65.5 million years ago

19. Major Events Dinosaurs appear Mammals appear Birds appear
Flowering Plants appear

20. Major Events
MASS EXTINCTION! - Hypothesized that the extinction occurred abruptly when a 10 km meteorite hit the Earth.

21. DOMINATE ORGANISMS
Reptiles
Dinosaurs
Conifer trees
Flowering Plants

22. Mesozoic Era pictures and fossils

23. The Cenozoic Era
65.5 million years ago – Present day

24. Major Events Mammals diversify (age of the mammals)
Forests dominate land
Grasslands appear

25. DOMINATE ORGANISMS
Wooly Mammoth
Primates
Mammals
Early humans

26. Cenozoic Era pictures and fossils