Continental Drift & Plate Tectonics
***Continental Drift
Wegner 1900's
Theory of Pangaea
Over time, this supercontinent drifted apart to what it is today.
***Plate Tectonics
Hess 1960's
The study of how and why "continental drift" exists.
It is the proof and evidence of it.
The lithosphere (crust) makes up the outer edge of the Earth. The crust is broken up into plates.
The asthenosphere (mantle) is filled with magma. It moves from convection. Because the magma is moving, the plates move as well.
The edges of plates that are together form boundaries. There are 3 types of movements in boundaries: divergent, convergent, and transform.
-Divergent means that the plates are pulling away from each other. This creates a ridge (mid-ocean ridge). It is called a rift valley. Iceland was made from this.
-Convergent means that the plates are going towards each other. There are 3 types on convergent movements as well: ocean to ocean, ocean to continent, and continent to continent. Mountain ranges are formed from the crushing of convergent continent plates. Because the density of the land masses are different, the denser land mass will go under (subduction, the process of a plate pushing under). It forms a trench. Island arc is when there are cracks in the plate caused by this, and then magma flows through it. Aleutian Islands are an example of this. Oceanic to continent convergence is different than ocean to ocean. Ocean to continent still forms a trench. Instead of an island arc, it forms a land volcano.
-Transform is a side to side movement. This sliding does not destroy land. These slide build up lots of pressure and cause earthquakes and friction.
The ring of fire is the edge of the pacific plate. There are lots of volcanic activity around the pacific plate
Wegner 1900's
Theory of Pangaea
Over time, this supercontinent drifted apart to what it is today.
***Plate Tectonics
Hess 1960's
The study of how and why "continental drift" exists.
It is the proof and evidence of it.
The lithosphere (crust) makes up the outer edge of the Earth. The crust is broken up into plates.
The asthenosphere (mantle) is filled with magma. It moves from convection. Because the magma is moving, the plates move as well.
The edges of plates that are together form boundaries. There are 3 types of movements in boundaries: divergent, convergent, and transform.
-Divergent means that the plates are pulling away from each other. This creates a ridge (mid-ocean ridge). It is called a rift valley. Iceland was made from this.
-Convergent means that the plates are going towards each other. There are 3 types on convergent movements as well: ocean to ocean, ocean to continent, and continent to continent. Mountain ranges are formed from the crushing of convergent continent plates. Because the density of the land masses are different, the denser land mass will go under (subduction, the process of a plate pushing under). It forms a trench. Island arc is when there are cracks in the plate caused by this, and then magma flows through it. Aleutian Islands are an example of this. Oceanic to continent convergence is different than ocean to ocean. Ocean to continent still forms a trench. Instead of an island arc, it forms a land volcano.
-Transform is a side to side movement. This sliding does not destroy land. These slide build up lots of pressure and cause earthquakes and friction.
The ring of fire is the edge of the pacific plate. There are lots of volcanic activity around the pacific plate