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