1. Today – 1/31 Timeline Weather report The CORE! Review session: Mon 5-7, Chavez 110

2. Continental Drift Proposed by Alfred Wegener in 1914 Continents were once together – Pangea, supercontinent

3. Evidence for Continental Drift Looks like a good fit Same fossils on different continents Same rocks on different continents Mountains line up across continents Paleoclimates line up across continents Problem: No Mechanism!

4. The CORE! Formed with Earth – magma ocean Know it’s there from seismic profiles

5. Seismic Waves Sound waves generated by earthquakes http://quake.wr.usgs.gov/info/listen/allsounds.html Two types of body waves: Primary = comPressional – faster Secondary = Shear – slower P-waves pass through fluid, S-waves don’t Density discontinuities deflect both

6. Density Discontinuities Sudden, sharp increases in density with depth Can be due to structurally and chemically different rocks (crust – mantle, mantle - core) Can be due to isochemical phase changes (major ones within the mantle and the core)

7. Compositional Layers of Earth http://www.ldeo.columbia.edu/~richards/Jefflec.html

8. Composition of The CORE! 85% iron, 5% nickel, 10% light element Cosmic abundance – missing on surface Magnetic field Density matches seismic data

9. Closed System A system is a part of the universe we choose to analyze. It’s surroundings are the rest of the universe The CORE! is a closed system – no mass leaves, only energy (heat) An open system exchanges both mass and energy with its surroundings

10. The outer core convects! Driven by “latent heat release” and the release of light elements that won’t fit into crystal structure of inner core Drives geodynamo – self-sustaining magnetic field!