8.4 – EARTH’S LAYERED STRUCTUREMrs. Guzman2/6/13

HOW 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

COMPOSITION VS. PROPERTIES

Properties Composition

Source: http://www.visionlearning.com/library/module_viewer.php?mid=69

Lower Mantle

LAYERS 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

CoreSphere composed mostly of

extremely dense iron-nickel alloy

LAYERS 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

HOW? Animation of P and S waves through the

interior: http://www.classzone.com/books/earth_science/t

erc/content/visualizations/es1009/es1009page01.cfm