Tectonic Plates and Continental Drift
Your planet isn't as solid as it seems - Earth's crust is actually broken into huge slabs of rock called tectonic plates that have been moving for 250 million years. This might sound mental, but scientists have loads of evidence to prove it.
Back in 1620, Francis Bacon spotted that Africa and South America fit together like jigsaw pieces, but it wasn't until German scientist Alfred Wegener studied this properly that we understood what was happening. Wegener theorised that all continents were once joined in a massive supercontinent called Pangaea.
Wegener's evidence was pretty convincing. He found identical fossils (like the fern Glossopteris and reptile Mesosaurus) on completely different continents separated by oceans. Coal deposits in Antarctica proved the continent was once tropical, and rocks of the same age and type appeared in both Africa and South America.
The movement happens because of convection currents in the mantle. Hot magma rises from the core, drags the continental crust along, then sinks when it cools down - like a massive underground conveyor belt that never stops.
Key Point: Scientists can track plate movement using paleomagnetism - magnetic particles in rocks that show which direction was "north" when the rock formed, proving continents have shifted position over time.