Plate Tectonics Objective: describe the theory of plate tectonics.
Plate Tectonics
description
Transcript of Plate Tectonics
Plate Tectonics
Earth Structure Quick reviewEarth is made up of
four main layers; crust, mantle, outer core and inner core.
Crust- on the outside, very thin and hard.
Mantle- The largest part making up 2/3 of the earth.
Outer Core- Lies above the inner core and is thought to be composed of mostly molten metal. Liquid.
Inner Core- Hottest place on Earth. Solid iron. Thought to create magnetic field.
The CrustWhat make up
the earth’s crust?
What is the lithosphere?
Crust consists of many continental and oceanic plates that have slowly moved and changed positions on the globe throughout geologic time.
The rigid upper part of Earth’s mantle and crust. The location of our plates.
Plate TectonicsWhat are
plates?
What is plate tectonics?
The Earth is broken up into pieces of land which move slightly around the Earth.
Very slow- movement can take more than a year to move a few centimeters.
Pieces of the lithosphere that move around.
Each plate has a nameFit together like jigsaw puzzlesFloat on top of mantle similar to ice
cubes in a bowl of water
Earth Plates
Alfred Wegener
He proposed that in the distant past, the Earth’s continents were all joined as a single landmass.
After putting all of Earth’s puzzle pieces together he named the land mass Pangaea.
Fossil Evidence
Plate tectonicsPlate
Boundaries-
Fault-
The places where the edges of different plates meet
Plates-1. Slide2. Separate3. Collide
Large fractures in rocks along which movement occurs.
How do Plates move?Plate
Movement1. Sliding
2. Separating
3. Colliding
Plates slide along each other, earth quakes commonly occur from the built up pressure.
When plates move apart, new crust forms to fill the gap between plates.
Tremendous force causing large mountains to form.
Divergent
Convergent
Transform
Three types of plate boundary
Divergent Boundaries
Spreading ridges*As plates move apart new material is erupted to fill the gap
Divergent Boundaries
Iceland has a divergent plate boundary running through its middle
Iceland: An example of continental rifting
There are three styles of convergent plate boundariesContinent-continent collisionContinent-oceanic crust collisionOcean-ocean collision
Convergent Boundaries
Forms mountains, e.g. European Alps, Himalayas
Continent-Continent Collision
Himalayas
Called SUBDUCTION
Continent-Oceanic Crust Collision
Oceanic lithosphere subducts underneath the continental lithosphere
Oceanic lithosphere heats and dehydrates as it subsides
The melt rises forming volcanism
E.g. The Andes
Subduction
When two oceanic plates collide, one runs over the other which causes it to sink into the mantle forming a subduction zone.
The subducting plate is bent downward to form a very deep depression in the ocean floor called a trench.
The worlds deepest parts of the ocean are found along trenches. E.g. The Mariana Trench is 11 km deep!
Ocean-Ocean Plate Collision
Where plates slide past each otherTransform Boundaries
Above: View of the San Andreas transform fault