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