Introduction to Plate Tectonic Theory

Introduction to Plate Tectonic Theory

IntroductionIntroduction

Plate tectonics is the theory that Earth's outer layer is made up of plates, which have moved throughout Earth's history.

The theory explains the how and why behind mountains, volcanoes, and earthquakes.

Plate tectonics is the theory that Earth's outer layer is made up of plates, which have moved throughout Earth's history.

The theory explains the how and why behind mountains, volcanoes, and earthquakes.

PangaeaPangaea

225 million years ago, all the major continents formed one giant supercontinent, called Pangaea.

Initiated by heat building up underneath the continent, Pangaea began to split apart, around 200 million years ago. These continents are still on the move today.

225 million years ago, all the major continents formed one giant supercontinent, called Pangaea.

Initiated by heat building up underneath the continent, Pangaea began to split apart, around 200 million years ago. These continents are still on the move today.

Theories of Plate MotionTheories of Plate Motion Exactly what drives plate

tectonics is not known. One theory is that convection

within the Earth's mantle pushes the plates.

Another theory is that gravity is pulling the older, heavier ocean floor with more force than the newer, lighter seafloor.

Exactly what drives plate tectonics is not known.

One theory is that convection within the Earth's mantle pushes the plates.

Another theory is that gravity is pulling the older, heavier ocean floor with more force than the newer, lighter seafloor.

Plate MotionPlate Motion

Plate tectonic activity takes place at four types of boundaries:

Divergent boundaries Convergent boundaries Collisional boundaries Transform boundaries

Plate tectonic activity takes place at four types of boundaries:

Divergent boundaries Convergent boundaries Collisional boundaries Transform boundaries

Divergent BoundariesDivergent Boundaries

Also known as spreading boundary, it occurs where two plates move apart, allowing magma, to rise from the Earth's interior to fill in the gap.

The two plates move away from each other like two conveyor belts moving in opposite directions.

Also known as spreading boundary, it occurs where two plates move apart, allowing magma, to rise from the Earth's interior to fill in the gap.

The two plates move away from each other like two conveyor belts moving in opposite directions.

Convergent BoundariesConvergent Boundaries

Also known as subduction boundary, it occurs where one plate slides under another as the two are pushed together.

If there is land at the edge of one of these plates, the ocean plate will subduct, or slide under that plate.

Also known as subduction boundary, it occurs where one plate slides under another as the two are pushed together.

If there is land at the edge of one of these plates, the ocean plate will subduct, or slide under that plate.

Collisional BoundariesCollisional Boundaries

A collisional boundary occurs where two land masses on plates are pushed together.

Trying to occupy the same space, the land masses buckle and fold, creating mountain ranges.

A collisional boundary occurs where two land masses on plates are pushed together.

Trying to occupy the same space, the land masses buckle and fold, creating mountain ranges.

Transform BoundariesTransform Boundaries

A transform boundary occurs where two plates slide against each other.

Rather than sliding smoothly, the plates build up tension, then release the tension with a spurt of movement called an earthquake

A transform boundary occurs where two plates slide against each other.

Rather than sliding smoothly, the plates build up tension, then release the tension with a spurt of movement called an earthquake

Birth of a Theory video questions

Birth of a Theory video questions

What led Wegener to his notion of continental drift?

What is and where does sea floor spreading occur?

How did paleomagnetism help support the notion of sea floor spreading?

What is a transform fault? Why is plate tectonic theory called a “model that

describes everything”?

What led Wegener to his notion of continental drift?

What is and where does sea floor spreading occur?

How did paleomagnetism help support the notion of sea floor spreading?

What is a transform fault? Why is plate tectonic theory called a “model that

describes everything”?