ENVS 2250 Chapter Notes -Peridotite, Solar Wind, Hydrosphere
2 Feb 2013
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Document Summary
Spins separately from the rest of the planet. Rotates in the same direction but 1 degree per year faster. The differential movement of material may be part of what generates a magnetic field: liquid outer core, 6972 km in diameter, 9. 7 12. 2 g/cm3. Heat is generates by the decay of radioactive isotopes such as potassium 40 (40k) which has a half life of 1. 25 billion years long enough to have generated heat throughout the earths history. Liquid when energy inputs are slow: drives movements of earths surface. The crust the brittle surface layer of the planet: thin and rocky, oceanic crust thinner and relatively young. Nowhere is it older than 200 millions years. Constantly being produced at mid-ocean ridges and recycled at continental margins. Denser than continental crust 3. 0 g/cm3. Subduction when oceanic crust slides underneath continental crust. Gabbro a coarse-grained rock formed when this magma cools a great depths.
