CONTINENTAL DRIFT

CONTINENTAL DRIFT THEORY

• The theory was introduced by Alfred Wegener in 1912.
• The theory stated that the world was once made up of a single continent called Pangea.
• The name Pangea means "all-earth".
• Wegener stated that the continents are not rigidly fixed but are moving at a rate of one yard per century.
• Pangea existed 300 million years ago.

CONTINENTAL DRIFT THEORY

• Pangea was originally one continent then split into two super continents called Laurasia and Gondwana.
• Then the two supercontinents split into the seven continents we know today.
• The continents are North America, South America, Antarctica, Africa, Australia, Europe, and Asia.
• Geologists originally had a hard time believing Wegener's continental drift theory.

WEGNER'S EVIDENCE

• Wegener needed to prove to other geologists that his theory could be trusted.
• The first way he did this was he showed them that there were the same fossils spread out on the other continents.
• Another way to convinced the geologists is that there are the same plant species spread into other continents.
• The next way he convinced them is that the continents look like they once fit together, like a puzzle.

HOW DO THE CONTINENTS MOVE?

• Geophysicist Harold Jefferys tried to disapprove of Wegener's theory by asking how did the continents move?
• Wegener suggested that the continents are floating on top of magma kind of like an iceberg floating on the water
• He proposed two different mechanisms for the drift; centrifugal force caused by rotation of the earth.
• Another mechanism was tidal argument based on the tidal attraction of the sun and the moon.

EFFECTS OF WEGENER'S DISCOVERY

• Decades later Wegener's theory of continental drift had sparked the theory of plate tectonics.
• This theory rose up newer questions about the earth's plates, and helped the discoveries of others.
• Plate tectonics is the theory of the earths surface containing tectonic plates that move very slowly.
• There are different types of plates for example transform and divergent.