Earth’s Moving Plates

Theory of Plate Tectonics Links the ideas of continental drift and ocean floor spreading and explains how the earth has evolved over time. Explains the formation, movement, collisions and destruction of the Earth’s crust.

Lithosphere Top most solid part of the earth

Lithospheric Plate Moving irregular shaped slabs that fit together to make the earths crust. There are 7 major plates which are different sizes and move at different speeds.

Plate Motion Convection currents move plates. Caused by differences in temperature.

Plate Boundaries Strike-Slip boundaries Divergent boundaries Convergent boundaries

Strike-Slip Boundary Formed by lateral faults. Nothing is created or destroyed. Earthquakes often occur.

Divergent Boundary Constructive boundaries Plates move apart at mid-ocean ridges. New crust is being formed at rift valleys.

Convergent boundaries Destructive boundaries Plates come together at trenches. Old crust is being destroyed through subduction. Pressure and friction cause earthquakes and volcanoes.

Oceanic vs. Continental Plate Collision Oceanic crust is subducted under continental crust. (ocean crust is more dense than continental crust) Volcanoes and mountains form

Continental vs. Continental Plate Collision Push together and upward to form mountains. (Crust is equally dense)

Oceanic vs. Oceanic Plate Collision The denser crust is subducted Island arcs and volcanoes form.