the earth’s structure. earth’s internal structure: compositional layers
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The earth’s structure
Earth’s Internal Structure: Compositional Layers
Crustthe outermost solid shell of a
rocky planet
Continental crust
thick (10-70km)- buoyant (less dense than oceanic crust) - mostly old
Oceanic crust
about 25 miles (32 kilometers) thick
- thin (~7 km)- dense (sinks under continental crust)- young
The LithosphereThe crust and the upper layer of the
mantle together
The Lithospheric Plates
The crust of the Earth is broken into many pieces called plates. The plates "float" on the soft,
semi-rigid asthenosphere.
Mantlelayer of the earth between
the crust and the core
Upper mantle
Lower mantle
The Asthenosphere
Largest layer
Convections currents
The Asthenosphere
the semi-rigid part of the middle mantle
flows like hot asphalt under a heavy weight.
Convection Currents
caused by the very hot material at the deepest part of the mantle rising, then cooling and sinking again
The middle mantle "flows" because of convection currents.
The Outer Core
composed of the melted metals nickel and
iron.
The Inner Core
Has temperatures and pressures so
great that the metals are
squeezed together and are not able to move about like a
liquid, but are forced to vibrate in place like a solid.
Elements in the crust
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