1. Volcanoes, Earthquakes, Tsunamis What do you know? What are some things you want to learn or questions you have?

2. Early History of Earth Formation by collision of material in the solar system – 4.6 billion years ago Bombarded with asteroids early on caused surface to be molten Gradually cooling 3.9 billion yrs. – Oceans formed  High iron content  Brown color – Atmosphere Mostly carbon dioxide Pink in color

3. Daily Review #1 1. Describe an organism that could have survived on Earth 3.9 billion years ago. 2. Approximately how old is Earth? 3. You are out hiking or walking along a path and notice a section rock like in the picture below. What questions would you have about that section of rock?

4. Absolute Dating Aka: radiometric or isotopic dating Tells an “exact” age Radioactive decay ◦ Parent nucleus becomes more stable daughter nuclei ◦ Give off energy ◦ Constant rate Half-life ◦ 100g → 50g + 50g ◦ → 75g + 25g

5. How do scientists use it? % parent left = # of half-lives → age What do we use? ◦ Carbon-14 ◦ Uranium-235 ◦ Potassium-40

6. Carbon Dating Various forms of carbon ◦ Most common = carbon-12 ◦ Radioactive = carbon-14 Carbon-14 ◦ Used for things that were alive ◦ During life - constantly replaced ◦ After death - amount starts to decrease ◦ Half-life of 5,730 years

7. Half-LifeFraction carbon -14 left Percentage carbon-14 left Age 1 2 3 4

8. You are a CSI Detective… You found a skeleton contains 12.5% of its original carbon. 1.How many half lives have passed? 2.How old is it? (how long ago did this person die?)

9. You are an anthropologist and found this animal! This skeleton contains 3.125% of its original carbon. 1.How many half lives have passed? 2.How old is it?

10. Daily Review #2 4. What happens in radioactive decay? 5. Define half-life. 6. The element chaparralium has a half-life of 24,000 years. If a fossil contains 25% of the original amount of chaparralium, how old is this fossil? Explain how you arrived at this answer. 7. What do you think happened to create the rock in this picture?

11. Relative Dating Order of events X is older/younger than Y Less specific Three major techniques

12. Where is the oldest part of your ice cream sundae? How are rocks similar? ◦ Law of superposition  Oldest…  Youngest… ◦ Principle of horizontality

13. What if the layers aren’t horizontal? Happened after rock cooled Folding ◦ Caused by pressure

14. Cross-Cutting Occur after rocks form Faults ◦ Caused by earthquakes ◦ Shift rock layers

15. Cross-Cutting cont. Intrusions ◦ Magma invades cracks ◦ Cools into rock ◦ Younger than surrounding rock

16. Tell the rock’s story…