Pg. 25

 After Earth formed, radioactive elements decayed and heat was released  Caused melting of interior  Denser elements sank to core (iron and nickel)  Process is still on going  Created layers

 Two different ways to define layers:  Composition  Physical properties

 Consists of 3 major layers defined by chemical composition:  Crust (silica)  Mantle (Fe and Mg)  Core (Fe and Ni)

 2 types: oceanic and continental  Oceanic is younger, made of basaltic rocks, and about 7 km thick  Continental crust averages about 40 km, average composition of granite  About 70% oceanic crust and 30% continental crust

 Contains of 82% of Earth’s volume  SOLID, rocky shell that extends to a depth of 2890 km  Boundary between crust and mantle represents a change in composition

 Composed of mostly iron and nickel  Incredibly dense  Tons of pressure

 Temperature and pressure affect the physical properties of rock  Material may behave like a brittle solid, a putty, or liquid  5 layers:  Lithosphere  Asthenosphere  Mesosphere (lower mantle)  outer core  inner core

 Outermost layer  Consists of crust and uppermost mantle  Relatively cool and rigid  About 100 km thick

 Soft, weak layer  Rocks are close to their melting point  Like hot wax

 More rigid than asthenosphere  Rocks are still hot and capable of flow but very slow

 Liquid layer  2260 km thick  Generates Earths magnetic field by flow of iron

 Radius of 1220 km  Compressed into a solid state because of pressure

 Used seismic waves from Earthquakes  Speed would change or waves would deflect when passing through different layers  Studied composition from meteorites, and experiments where rock is heated and pressurized

 Create a diagram that shows the difference between Earth’s layers being separated by chemical composition and physical properties  Color it to show the difference between the two  List characteristics of each layer in your drawing