Dynamic Earth Practice Test

Paleomagnetism in rocks records the direction of Earth's magnetic field at the time the rock formed. When you compare paleomagnetic data from rocks of the same age on different continents, you find that the recorded pole positions line up in a way that can only be reconciled if those landmasses were connected and moving together. Reassembling the continents into one map makes these magnetic records fit a single, coherent pattern of pole positions over time, which is exactly what you’d expect if a supercontinent once existed. This coordinated signal across continents is the strongest clue for past continental unity like Pangaea. Magnetic data are valuable not just on the ocean floor but on continents too, and magnetic reversals are global events recorded everywhere, not opposite poles confined to different continents.