plates
The Structure of the Earth and
Plate Tectonics
Structure of the Earth
Mantle
• The Earth is made up of 3 main layers:
Outer core
Inner core
– Core
– Mantle
– Crust
Crust
The Crust
• 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
How do we know what the
Earth is made of?
• Geophysical surveys: seismic, gravity, magnetics, electrical, geodesy
– Acquisition: land, air, sea and satellite
– Geological surveys: fieldwork, boreholes, mines
What is Plate Tectonics?
•
If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle.
Plate Tectonics
• The Earth’s crust is divided into 12 major plates which are moved in various directions.
• This plate motion causes them to collide, pull apart, or scrape against each other.
• Each type of interaction causes a characteristic set of Earth structures or “tectonic” features.
• The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction.
World Plates
What are tectonic plates made of?
• Plates are made of rigid lithosphere. The lithosphere is made up of the crust and the upper part of the mantle.
What lies beneath the tectonic plates?
• Below the lithosphere (which makes up the tectonic plates) is the asthenosphere. Plate Movement
• “Plates” of lithosphere are moved around by the underlying hot mantle convection cells
Practical Exercise 1
Supercontinents!
What happens at tectonic plate boundaries?
Three types of plate boundary
• Divergent
• Convergent
• Transform
Divergent Boundaries
• Spreading ridges
– As plates move apart new material is erupted to fill the gap
Age of Oceanic Crust
Courtesy of www.ngdc.noaa.gov
Iceland: An example of continental rifting
• Iceland has a divergent plate boundary running through its middle
Plate Tectonics
Structure of the Earth
Mantle
• The Earth is made up of 3 main layers:
Outer core
Inner core
– Core
– Mantle
– Crust
Crust
The Crust
• 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
How do we know what the
Earth is made of?
• Geophysical surveys: seismic, gravity, magnetics, electrical, geodesy
– Acquisition: land, air, sea and satellite
– Geological surveys: fieldwork, boreholes, mines
What is Plate Tectonics?
•
If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle.
Plate Tectonics
• The Earth’s crust is divided into 12 major plates which are moved in various directions.
• This plate motion causes them to collide, pull apart, or scrape against each other.
• Each type of interaction causes a characteristic set of Earth structures or “tectonic” features.
• The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction.
World Plates
What are tectonic plates made of?
• Plates are made of rigid lithosphere. The lithosphere is made up of the crust and the upper part of the mantle.
What lies beneath the tectonic plates?
• Below the lithosphere (which makes up the tectonic plates) is the asthenosphere. Plate Movement
• “Plates” of lithosphere are moved around by the underlying hot mantle convection cells
Practical Exercise 1
Supercontinents!
What happens at tectonic plate boundaries?
Three types of plate boundary
• Divergent
• Convergent
• Transform
Divergent Boundaries
• Spreading ridges
– As plates move apart new material is erupted to fill the gap
Age of Oceanic Crust
Courtesy of www.ngdc.noaa.gov
Iceland: An example of continental rifting
• Iceland has a divergent plate boundary running through its middle