Download The Structure of the Earth and Plate Tectonics

• The Earth is made
up of 3 main
layers:
– Core
– Mantle
– Crust
Crust
Mantle
Outer core
Inner core
• This is where we live!
• The Earth’s crust is made of:
Continental Crust
Oceanic Crust
- thick (10-70km)
- buoyant (less dense
than oceanic crust)
- mostly old
- thin (~7 km)
- dense (sinks under
continental crust)
- young
• The Earth’s crust and upper
mantle are broken into sections
called plates.
• Plates move around on top of the
mantle like rafts.
• Plates are made
of rigid
lithosphere.
The lithosphere is made up
of the crust and the upper
part of the mantle.
• The crust and part of the upper
mantle =
–100 km thick.
–Less dense than the material below
it, so it “floats”.
• Below the
lithosphere
(which makes up
the tectonic
plates) is the
asthenosphere.
• The plastic layer below the
=
• The plates of the
float on the
- plates below the
oceans.
- plates
below the continents.
• Hot magma in the Earth moves
toward the surface, cools, then
sinks again.
• Creates convection currents
beneath the plates that cause the
plates to move.
• “Plates” of lithosphere are moved around by the
underlying hot mantle convection cells
There are three types of boundaries where
crustal plates meet:
•
•
•
• Also called rift zone.
• Plates moving apart.
• Sea floor is created by sea floor spreading.
• Forms mid-oceanic ridges.
Age of Oceanic Crust
Courtesy of www.ngdc.noaa.gov
• Boundaries between two plates
that are colliding
 
• There are 3 types…
• Ocean plate colliding with
continental plate.
• Subduction Zone: where the
oceanic plate slides under the
continental plate.
• VOLCANOES occur at subduction
zones
Andes Mountains,
South America
• Ocean plate colliding with
another ocean plate.
• The less dense plate slides under
the more dense plate creating a
subduction zone called a
TRENCH.
• A continental plate colliding with
another continental plate.
• Have Collision Zones:
–a place where folded and thrust
faulted mountains form.
Himalayas
• Plates move / slide past each other.
• Faults are formed.
• Earthquakes along faults.
Example: San Andreas Fault
• The Earth is made up of 3 main layers (core,
mantle, crust).
• On the surface of the Earth are tectonic plates
that slowly move around the globe.
• Plates are made of crust and upper mantle
(lithosphere).
• There are 2 types of plate.
• There are 3 types of plate boundaries.
• Volcanoes and Earthquakes are closely linked to
the margins of the tectonic plates.