The Theory of the Shifting Continents & Pangea

Paleomagnetism

• Paleomagnetism is a major component in Alfred Wegener's reasoning for the continental drift theory. It occurs when magma comes to the surface from inside of the Earth. As it cools, the minerals become magnetized by the planet's magnetic field. Studies of rock layers for magnetic minerals show that the magnetic poles have moved over a period of time.

Fossils

• Fossil matches are seen as validation that continental drift occurred. Animals found on several continents such as Antarctica might match those of northern continents. For example, Mesosaur fossils have been discovered in South America and Africa. Fossilized plants have also been discovered that act as evidence of continental drift. The Glossopteris remains appear in several continents, including Australia.

Movement

• Some scientists think that the tectonic plates move like rafts, floating below the Earth's surface. The mantle is hot and semi-solid, and currents inside the Earth move plates across the mantle. Another theory is that plates move like rafts being pulled around and the cold seabed at the edge of the ocean sinks into the mantle. This causes pulling that forces the plate to move. The speeds at which the plates move are calculated by reversals of the earth's magnetic fields and the duration of each reversal. For example, the Arctic Ridge moves the slowest while the East Pacific Rise moves the fastest.

The Future

• It is commonly thought that the makeup of continents in the future will not appear as it does today. Some scientists think that continents will come together to form Pangea Ultima in around 250 million years and there will be just the Atlantic Ocean that will be the inland sea. The conjectures for 50 million years into the future are that Africa will continue to move north, closing off the Mediterranean. Australia will come in contact with Asia and the Americas will be further away from Europe as well as Africa because of Atlantic Ocean's sea floor growth. Earth is the only planet in this solar system that still has active volcanoes and tectonic movement. At some point, Earth will lose much of its heat as it finally cools, bringing continental movement to a stop. The geological cycle, including forming new mountains and creating new soil, will also stop.