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.