1. Lecture 3 Science is built of facts the way a house is built of bricks, but an accumulation of facts is no more science than a pile of bricks is a house. ’ - Henri Poincare’ Creation and development of the Earth Webpage for course (daytime) Webpage for course (nighttime)

2. Observations about our Solar System 1. planets, moons, asteroids form ring @ sun 2. all these revolve in same direction 3. most have similar orientations 4. most rotate in same direction, as does sun 5. many moons have same general features 6. distribution of planets Terrestrial vs. Jovian

3. Nebula Hypothesis

5. Earliest structure of the earth unsorted mix of compacted gas and dust?

6. How did earth become molten? Sources of heat - impact of meteorites - compression - radioactive decay

9. This history explains Thin crust Differentiation of earth by density heavy material in middle of earth (core) lighter material in crust intermediate density in mantle Formation of atmosphere convection cells in mantle

10. Thin crust and convection cells in mantle help account for - plate tectonics (continental drift) - mountains - erosion and deposition

11. Our earth is a very active planet

12. Nature’s Law is change; constancy is strange.