What is the tectonic cycle? briefly summarize it.

In simple terms, heavier plates get melted in Mantle, become lighter in form of lava and create new plates. As we have a re-cycle or the convection currents, there are cycles in lithosphere.
There is continuous push and pull happening on and below the Earth. When a plate is subducting on one end, there has to be some reaction on the other end, right?
Ridge is developed on the other side, where the same material which has been melted on the subduction side helps to fill the gap at ridge side. Since the material is just transfered from heavy to light, and reused in that cell, it is called a cycle.
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