Plate tectonics is the scientific theory explaining the movement of the earths crust. The movement of these tectonic plates is likely caused by convection currents in the molten rock in earths mantle below the crust. Earthquakes and volcanoes are the short term results of this tectonic movement.

Continental drift theory describes the long term effect of plate tectonics.

Explanation:

The long term result of plate tectonic movement is the continental drift. The continents of Earth lay on tectonic plates, that are in motion and interaction via plate tectonics. The drift of the Earths continent is an ongoing process evident in the rift valleys and seafloor spreading zones.

The theory that  the Earth's continents are dynamic and have drifted relative to each other is known as continental drift which correlates with the theory of plate tectonics.

Every year, the Earth's outer shell plates are displaced by a small amount due to the heat coming from the Earths interior via convection currents.

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