It’s been estimated that in all of Earth’s history, there have been 7 supercontinents, with the most recent one being Pangaea.
The next supercontinent (Pangaea Ultima) is expected to form in around 250 million years.
Why is this the case? What phenomenon causes these giant landmasses to coalesce, break apart, then coalesce again?
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If you want a more nuanced answer than just “that’s what they do” I’ll do my best.
So plate tectonics is driven by multiple sources of energy. When rifting occurs it “pushes” the plates away from spreading centers and when subduction occurs it “pulls” the oceanic plates and all of this energy is driven indirectly by convection cells in the mantle. Some of the statements I just gave you are simplifications and/or up for debate.
But based on what tectonic regimes are at play globally, the continents tend to be pushed together when continental rifting occurs less and subduction zones occur more often. Why these paradigms change is a much more complex conversation.
The geometry of a sphere that the continental plates are essentially floating across they are bound to collide given enough time, just kinda a statistics thing. Or like when you take two strings and jostle them around in a box they become tangled and knitted.
When continental rifting happens at accelerated rates the continents tend to diverge.
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