3. Convection Currents

Plate movement and Convection Currents

PLATE MOVEMENT

The earth's crust is made up of pieces we call plates. These large

pieces of crust are moving. Earthquakes are caused by the crust moving. Earthquakes can happen anywhere on a plate, but if two plates move beside each other, there can be massive earthquakes and catastrophic damage. The edge of plates are called plate boundaries. When plates move beside each other massive earthquakes occur at the plate boundary. Some plates have large landmasses on them we call

TEACHING CLIP - NG Tectonics

CONVECTION CURRENTS

No single plate can move without affecting others in some way at its boundaries.

The plates are being moved by energy created by convection currents from the mantle below.

Convection currents are currents of magma that is heated by the energy of the core. This heated magma is less dense and lighter, and rises to the underside of the crust. There, it is redirected under the crust, cooling and becoming more dense (heavier) as it flows. As it flows under the crust it can push or pull the crust with it. Once cooler, it begins to descend back towards the core. At the core it is heated again, repeating the cycle and creating individual convection cells.

CONVECTION CELLS

Convection cells are the result of the convection currents heating and cooling and reheating. Each individual loop is called a convection cell. This moving "river" of magma pulls on the underside of the crust as it flows beneath it. If there are convection currents moving in different directions under neighboring plates, the force can cause the plates to collide, move apart or sometimes slide by each other in different directions.