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 .