Transcript divergent boundary. Results in volcanos and seafloor spreading

Plate Tectonics
and Continental Drift
Continental Drift
A theory from Alfred Wegener
States that continents can drift apart from one
another and have done so in the past
Continental Drift
This helps to support Pangea
Pangea was a landmass of all continents
together
Pangea means “all earth”
Continental Drift
Evidence of Continental Drift
Continents seem to fit together
Fossils of same plants and animals are
found on both sides of the Atlantic Ocean
Seafloor 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 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 Tectonics
Plate tectonics is the theory that Earth’s
lithosphere is divided into plates that move
around on top of the asthenosphere.
What makes them
move???
3 Possible forces:
Ridge Push
Convection
Slab Pull
Plate Boundaries
Plates can move 3 different ways.
Collide, separate, or slide past one another
Plate Boundaries
When two plates meet and they push into one
another it is called a convergent boundary.
Results in mountains and volcanos
Plate Boundary
Areas where oceanic plates sink down into the
asthenosphere is called a subduction zone.
Plate Boundary
When two plates move away from one another
we call it a divergent boundary.
Results in volcanos and seafloor
spreading
Plate Boundary
When two plates slide past one another the
boundary is called a transform boundary.
Results in a lot of earthquakes!
Movement of Plates
Plates move so slow you can’t feel or see
them.
Centimeters per year!
Motion is monitored through GPS systems.
EXIT 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 .