The Earth & Plate Tectonics - Chapter 1

Crust

Outer layer of the Earth. It is made from solid rock and ranges from 5 to 70km in depth. The Earth’s crust is divided into pieces that move.

Mantle

Found underneath the Earth’s crust and consists of semi-molten or molten rock called magma.

Outer Core

Consists of liquid nickel and iron

Inner Core

Solid ball in the center of the earth

Convection Currents

• Magma in the mantle is heated. It becomes lighter and rises

• When the hot magma reaches the underneath or the crust, it spread in all direction, dragging the crust with it

• The magma cools slightly and sinks through the mantle and starts to heat up again

  • This process is repeated again in circular motions, causing convection currents

Alfred Wegener

German scientist who proposed the theory of continental drift

Tectonic plates

Pieces of the crust

Magma

Semi-molten rock

Continental drift

The process where continents broke apart and moved.

Pangaea

The name given to the landmass 250 million years ago when all continents were connected.

Molten

The word used to describe hot, melted rock.

Plate

A large slab of the earth's crust.

Plate boundary

Where plates meet

Destructive plate boundaries

• Plates collide

• Heavier (oceanic) plate sinks (subducts) under lighter plate

• Magma rises = Volcanoes & Earthquakes

  • Example: Pacific Ring of Fire

Conservative plate boundaries

• Plates slide past each other

• No crust created/destroyed

• Earthquakes only

  • Example: San Andreas Fault (USA)

Constructive plate boundaries

• Plates move apart

• Magma rises → new crust forms → volcanoes

• Example: Mid-Atlantic Ridge (Iceland)

C-D-P

• Constructive = Creates crust

• Destructive = Destroys crust

• Passive = Plates slide