1. HOW DID WE GET HERE?? EARTH AND THE ORIGIN OF LIFE

2. CHANGE IS SLOW! http://www.youtube.com/watch?v=RtyqS68ViWk

3. CYCLE ONE REVIEW

4. EARTH IS LAYERED The internal structure of the earth is divided into layers tectonic plates Shifting causes earthquakes, volcanic eruptions, formations of mountains

5. THE HYDROLYTIC CYCLE Made up of all water on Earth Solid, liquid and gas Water cycle transports water around the Earth Energy from the sun

6. THE ATMOSPHERE Protects Earth from harmful solar radiation and extreme temperature changes Made up of combination of gases Nitrogen Oxygen Other: argon, carbon dioxide, ozone, water vapour, etc.

7. THE LITHOSPHERE The rigid outermost shell of the Earth Made up of the crust and part of the upper mantle

8. EROSION The deteriorating effect that water and wind on rocks and soil Debris from erosion is called sediment Each layer of sediment is called strata Earth shows signs of past events in the strata Geological scale Biological level

9. YOUR TURN Write a summary in your own words of what we just learned

10. QUESTIONS How old is the Earth? What are the events that led to the formation of the solar system? Which conditions led to the emergence of life? When did life first appear on Earth?

11. THE FORMATION OF EARTH CHANGE IS SLOW

12. 4.6 BILLION YEARS AGO Small particles of gas and dust slowly started coming together Created the solar system The sun formed in the center of the cloud of particles Other planets formed around the sun

13. 4.2 BILLION YEARS AGO Part of the gas and dust condensed to form Earth Intense heat and pressure at core melt rocks Earth cools creating solid rock BUT Earth’s core remains extremely hot

14. 4.2-3.9 MILLION YEARS AGO Earth is bombarded with asteroids, meteors and comets Giant impact hypothesis Formation of the moon

15. 3.5 BILLION YEARS AGO Oceans and atmosphere develop Atmosphere made up of volcanic gages Triggers rain Fills oceans Rocky surfaces not underwater form continents

16. YOUR TURN Key ideas: 1.. 2.. 3.. 4..

17. THE ORIGIN OF LIFE

18. Earth is unique Only planet in the solar system capable of sustaining life Since the formation of the planet, Earth has undergone many changes 1 billion years between the formation of Earth and the emergence of life

19. Scientists use Fossil evidence suggests life emerges 3.5 billion years ago