Why is there a continental drift?

The continental drift phenomenon has been noticed a long time ago: Already at the end of the 16th century, a new hypothesis was formulated, based on continental shapes, after noticing their perimeters (as drawn by coastal lines) could fit together.
In 1912, climatologist Alfred Wegener proposed the theory of continental drift, hypothesizing that all current land mass evolved from a primordial super-continent which he named Pangaea…

Today’s continents emerged from Pangaea because of the convergence of tectonic plates, the large scale motions of the Earth’s lithosphere, which is a solid layer (thickness averaging between 0 and 30km) and which combines with the continental crust (also solid, with a thickness between 30 to 75km).
The lithosphere “floats” on a softer, higher temperature layer named asthenosphere, where rock is fused into magma.
This high-temperature activity creates a movement affecting the upper, solid layers, making them move in a convergent, divergent or lateral manner.
This movement itself has transformed the super-continent Pangaea into those we know today.