​A rigid layer made up of the uppermost part of the mantle and the crust.

​​lithosphere

​The upper layer of the Earth’s mantle, below the lithosphere, in which there is plastic flow and convection occurs.

​​Asthenosphere

​Alfred Wegener’s 1912 theory that all continents had been a single giant continent called Pangaea but did not offer a process for how it was happening.

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continental drift theory

​Magma from the asthenosphere pushes up through a rift in the seafloor and solidifies into new crust, forming a ridge and pushing the existing crust off to the side. Old seafloor is carried along with convection currents and drawn down by gravity in deep sea trenches.

seafloor spreading theory

Circular currents in the mantle caused by the magma being heated by the core of the Earth.

​convection currents

​Combination of continental movement from Continental Drift Theory, using Seafloor Spreading Theory as the process of how the movement is happening.

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plate tectonics theory