Plate Tectonics and Continental Drift. Continental Drift A theory from Alfred Wegener States that continents can drift apart from one another and have.

Plate TectonicsPlate Tectonicsand Continental Driftand Continental Drift

Continental DriftContinental Drift

A theory from Alfred Wegener

States that continents can drift apart from one another and have done so in the past

Continental DriftContinental Drift

This helps to support Pangea

Pangea was a landmass of all continents together

Pangea means “all earth”

Continental DriftContinental DriftEvidence of Continental Drift

Continents seem to fit together

Fossils of same plants and animals are found on both sides of the Atlantic Ocean

Seafloor SpreadingSeafloor Spreading

Many years later the thought of seafloor spreading was introduced.

Seafloor spreading is the process where new oceanic lithosphere is created as materials are pulled away.

As plates move apart, the seafloor spreads apart and magma rises to fill in the gap.

Seafloor SpreadingSeafloor Spreading

Mid-ocean ridges occur at areas of seafloor spreading

Mid-ocean ridges are underwater mountain chains

The Mid-Atlantic Ridge is the largest mountain chain in the world.

Plate TectonicsPlate TectonicsPlate tectonics is the theory that Earth’s lithosphere is divided into plates that move around on top of the asthenosphere.

What makes them move???

What makes them move???

3 Possible forces:

Ridge Push

Convection

Slab Pull

Plate BoundariesPlate Boundaries

Plates can move 3 different ways.

Collide, separate, or slide past one another

Plate BoundariesPlate Boundaries

When two plates meet and they push into one another it is called a convergent boundary.

Results in mountains and volcanos

Plate BoundaryPlate Boundary

Areas where oceanic plates sink down into the asthenosphere is called a subduction zone.

Plate BoundaryPlate BoundaryWhen two plates move away from one another we call it a divergent boundary.

Results in volcanos and seafloor spreading

Plate BoundaryPlate Boundary

When two plates slide past one another the boundary is called a transform boundary.

Results in a lot of earthquakes!

Movement of PlatesMovement of Plates

Plates move so slow you can’t feel or see them.

Centimeters per year!

Motion is monitored through GPS systems.

EXIT SLIPEXIT SLIP

Describe continental drift theory.

What are the 2 main pieces of evidence for continental drift?

Name the 3 types of plate boundaries.

Describe the movement at each plate boundary and what results from each .