The theory of plate tectonics was introduced in the 1960s to explain how the Earth's plates move and to provide some understanding as to how volcanoes, earthquakes and tidal waves occur. The theory of plate tectonics also explains mountain range formation, ocean ridges and undersea trenches. It's not difficult to effectively teach children the theory of plate tectonics.
Location
There are presently several known and named plates including the Australian-Indian plate, Eurasian plate, Pacific plate, Philippine plate, North American plate, South American plate, Caribbean plate, African plate, Arabian plate, Antarctic plate, Scotia plate, Juan de Fuca plate, Nazca plate and the Cocos plate. Explain to children how these plates fit somewhat like a jigsaw puzzle, except that this puzzle changes and moves.
Types of Movement
There are three types of plate movement in the theory of plate tectonics. Divergent plate movement is when the plates move away from one another, resulting in the spreading of the sea floor. New oceanic crust forms from magma from the mantle. This occurs along mid-ocean ridges. Convergent plate movement happens when two plates collide. When this happens with an oceanic plate and a continental plate, the oceanic plate is forced under the continental plate. When convergent plate movement occurs with two oceanic plates, one may get pushed under the other, resulting in magma rising from the mantle and the formation of volcanoes. When convergent movement occurs with two continental plates, mountain ranges are formed as two crusts are compressed and move upward. Lateral slipping plate movement is when the plates move sideways against each other and a great deal of friction results in jerky-type movements. This action builds pressure, which suddenly releases, forcing the plates apart and creating earthquakes.
Changes to the Earth
All this motion and constant change means the earth is always evolving. Sea levels change due to variations in earth temperatures or freezing or melting at the North and South Poles, and thus different amounts of crusts are exposed. Most plates are hidden by oceans, but they can be mapped by Geosat satellites. Plates can change greatly over time or disappear entirely. For instance, the Juan de Fuca plate is what remains of the larger Farallon plate, and it is eventually going to sink beneath the North American plate, according to the US Geologic Society.
Tags: plate movement, theory plate, American plate, plate tectonics, plates move, theory plate tectonics, when plates
