Events
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.
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