Earth’s Layered Structure

 Crust  Mantle  Core

 Thin, rocky outer layer of earth  Divided into oceanic and continental crust

 Oceanic Crust  7 km thick  Consists of igneous rocks  Density of rocks=2.7g/cm3  Rocks are much younger  Continental Crust  8-75 km thick;average thickness =40km.  Consists of a variety of rocks- mostly granite  Density of rocks=3.0g/cm3

 82% of Earth’s volume is found here  A solid, rocky shell that extends to a depth of 2890 km.  Periodite is a common rock found in the uppermost mantle, density=3.4g/cm3  The boundary between the crust and mantle indicates a change in chemical composition.

 A sphere made mostly of an iron-nickel alloy.  In the center of the core extreme pressures exist producing an average density of 13 g/cm3.

 The lithosphere  The asthenosphere  The lower mantle  The outer core  The inner core

THE LITHOSPHERETHE ASTHENOSPHERE  Earth’s outermost layer made of the crust and upper mantle  Forms a relative cool shell  This layer averages 100km in thickness  Soft and weak layer of Earth  A rigid shell that averages 100km in thickness.

LOWER MANTLEINNER AND OUTER CORE  Located 660km down near the base of the mantle.  The rocks here are very hot and can gradually flow  Composed mostly of Fe & Ni alloy.  Outer core is a liquid layer 2260 km thick and produces the magnetic field.  The Inner core has materials that are compressed into a solid state due to extreme pressures.

 Studies of the paths of p and s waves through Earth ‘s layers helped identify boundaries and that the outer core is liquid.  st evidence of layering within the Earth’s mantle; created the Moho boundary.  1906 another boundary was discovered between the mantle and the outer core.

 Scientists studied seismic data, rock samples from the crust and mantle, meteorites, and high pressure experiments on Earth materials.