1. 8.4 – E ARTH ’ S LAYERED STRUCTURE Mrs. Guzman 2/6/13

2. H OW DO THEY KNOW ? Scientists cannot “see” into the interior of the Earth, so they can INFER what is in there based upon studying: The behavior of earthquake waves (energy) Material from meteroites Experimentation with materials

3. C OMPOSITION VS. PROPERTIES

4. Properties Composition Source: http://www.visionlearning.com/library/module_viewer.php?mid=69 Lower Mantle

5. L AYERS BY COMPOSITION Crust thin, rocky outer layer. Contains both oceanic (7km) and continental crust (8- 75km). Composed of granite and granodiorite Mantle Solid rocky shell between crust and core. Extends ~ 2890 km. Composed of peridotite Core Sphere composed mostly of extremely dense iron-nickel alloy

6. L AYERS BY PHYSICAL PROPERTIES Changes in temperature, pressure, and density with depth that determine how each layer behaves (it’s properties) Lithosphere = outermost layer. Consists of crust and uppermost mantle. Cool, rigid shell about 100km thick Asthenosphere = soft, weak layer. Rocks are close to melting and are easily deformed Lower Mantle = rigid layer from 660km down to the bottom of the mantle. Strong, but capable of being deformed *Inner and Outer Core Outer = liquid layer 2260 km thick. Made of metallic iron that creates magnetic field Inner = radius of 1220 km. High temps, but material is solid due to very high pressure

7. HOW? Animation of P and S waves through the interior: http://www.classzone.com/books/earth_science/terc/co ntent/visualizations/es1009/es1009page01.cfm http://www.classzone.com/books/earth_science/terc/co ntent/visualizations/es1009/es1009page01.cfm