PLATE TECTONICS

THE MAIN LAYERS OF THE EARTH

Lithosphere: Crust and solid upper mantle.

Asthenosphere: Plastic, movable part of the mantle.

Outer

WHY CRUST MOVES:

Heat from the inner core cause convection currents to flow within the asthenosphere.

Rising currents cause plates to move apart

Sinking currents cause plates to come together.

DIVERGENT PLATE BOUNDARIES

Location where two plates are moving apart

Diverging plates cause rift valleys to form

Examples (Mid-Atlantic Ridge and East Pacific Rise, East African rift valley)

CONVERGENT PLATE BOUNDARIES

There are 3 types of converging Plate boundaries (continent-ocean, ocean-ocean, continent-continent)

Converging plate boundaries create mountains, volcanoes, and deep trenches to form

TRANSFORM PLATE BOUNDARIES

These boundaries occur when plates are forced to slide past one another

The average rate of movement is 5 cm per year

Some spots have not moved for centuries

PASSIVE PLATE BOUNDARIES:

- Occur where ocean crust and continental crust meet but do not subduct.