1. Geologic Time

2. Learning Objectives Describe Earth’s early history
Describe the characteristic forms of life in the Paleozoic, Mesozoic and Cenozoic eras

3. Geologic Time Scale
A record of life and events on Earth

4. Geologic Time Scale EONS ERAS
PERIODS
EPOCHS
Because the Earth is so old, a geologic time scale is used to show Earth’s history.

5. Precambrian Earth Asteroids and meteors bombard the surface
shallow seas form
bacteria-like organisms appear
Hot gases from volcanos

6. Diverse life appears and evolves
Paleozoic Era: mya
Diverse life appears and evolves

7. Cambrian Explosion
Many different invertebrate critters evolve

8. First Vertebrates
Ordovician Period: Jawless fish appear

9. Silurian Period
Life reaches land, plants become abundant

10. Devonian Period
Animals invade the land, amphibians evolve

11. Permian Era
Pangaea supercontinent is formed

12. First Mass Extinction
First mass extinction marks the end of the Paleozoic Era

13. The Mesozoic Era: 245 – 66 mya
Age of the Dinosaurs

14. Triassic Period
Plants and animals that survived the mass extinction include insects, fish, reptiles, mammals and cone bearing trees

15. Dinosaurs become the dominant animal
Jurassic Period
Dinosaurs become the dominant animal

16. Cretaceous Period
Flying reptiles and birds compete for places in the sky

17. Mass Extinction #2
End of the 65 million year dinosaur age

18. Cenozoic Era 66 mya - present
Age of the mammals

19. Warm climates, evolving marine animals, and flowering plants
Tertiary Period
Warm climates, evolving marine animals, and flowering plants

20. Quaternary Period Changing environment, large mammals,
ice ages, and homo sapiens

21. YouTube Geologic Time Scale

22. Stop Here