Plate Tectonics - Timeline

Abraham Ortelius Proposes Continental Drift Ortelius was the first person to see the east coast of South America and the west coast of Africa fit together. He proposed the idea that continents drifted over time as an explanation.

Nicolaus Steno's Law of Superposition Nicolaus Steno studied rock layers in the mountains of Italy, finding that rocks that were older were lower down compared to younger rocks. This was known as the law of superposition.

James Hutton Presents Uniformitarianism In 1785, James Hutton presented uniformitarianism to the Royal Edinburgh Society. His principle stated that geological processes happen at a constant speed over time. This was a stark contrast to the 'catastrophic' belief at the time, which was that mountains and other landforms were created by God in a short period of time.

Alfred Wegener Discovers Proof of Continental Drift Wegener discovered similar fossils along the matching coastlines of South America and Africa, reasoning that the organisms wouldn't have been able to cross the Atlantic Ocean. Therefore, the only rational explanation was that the two continents were once joined. He referred to this prehistoric continent as 'Pangaea'.

Arthur Holmes Presents Convection Current Theory Wegener's theory was disputed by the scientific community due to lack of a mechanism of movement moving the plates. Arthur Holmes proposed that convection currents within the asthenosphere caused plates to move.

Harry Hess's Theory of Seafloor Spreading In 1962, Harry Hess proposed that the convection currents caused the sea floor to spread out from a central point, taking the continents with it.

Dan Mckenzie's Theory of Plate Tectonics In 1968, Dan Mckenzie tied together the theories of seafloor spreading and continental drift under a single theory - 'plate tectonics'. He proposed that the crust was partitioned into plates, which interacted with each other, creating phenomena such as volcanoes, mid-ocean ridges and trenches.