How Earth’s Plates Move

Plate Tectonics

The Lithosphere• The plates of the lithosphere

fit together like puzzle pieces and float on the asthenosphere.

• Plates moving away from each other along a divergent boundary.

• Plates collide on a convergent boundary.

• Plates grind past on a transform fault boundary.

Boundaries

• Divergent boundary, plates move apart and magma oozes up forming a new crust.

• Convergent boundary plates move together and one moves over the top of another.

• Transform fault boundary plates grind past without forming or melting crust.

Divergent Boundaries

• Scientists believe magma is being pushed up and the pressure pushes the plates apart.

• Divergent boundaries form on mid-ocean ridges at the rift.

• New magma moves up, cools and forms new sea floor in a process called sea-floor spreading.

Convergent Boundaries

• Three kinds of convergent boundaries can exist.

• First,ocean plates collide and one is pushed under the other. This is how ocean trenches form.

• Second, when land plates form and one crumples under the other and new mountains form.

Third, when an ocean plate collides with a continental plate and the ocean plate is forced down. Ocean crust is denser than continental crust.

Mountains and volcanoes form here.

Transform Fault Boundaries

• This boundary is when two plates move past each other in opposite directions.

• The San Andreas fault is a fault dividing California into two plates.

• Earthquakes are common at these fault lines.

Earth’s Surface Changes

• Earth’s surface is continually changing and always will change.

• Plates move around the Earth’s surface and cause new mountains to form and new oceans to form.