1. Theory of Continental Drift  A German scientist, named Alfred Wegener was one of the first scientist to propose that continents had once been closer together.  Wegener called this idea “Continental Drift.” His idea was not widely accepted because scientist believed that the continents and oceans were permanent features fixed in their position and did not move. Reference: Pages 514 - 515

2. Theory of Continental Drift  Hundreds of millions of years ago, a supercontinent called, “Pangaea” once existed. At approximately 200 million years ago, this landmass split into smaller pieces and drifted apart reaching their present positions. Wegener’s idea was;

3. Theory of Continental Drift Wegener’s main criticism centered around why the continents move.  Wegener suggested that the continents plow through the oceans as a snow plow would trough snow. This reasoning for the movement of continents was not widely accepted.  A weakness in Wegener’s theory was it could not satisfactorily answer the question asked by critics: What kind of forces could be strong enough to move such large masses of solid rock over such great distances?

4. Theory of Continental Drift  After Wegener’s death in 1930, much evidence was discovered to support the Continental Drift Theory.  Holmes suggested that continents and the ocean floor move primarily due to forces in the asthenosphere (upper mantle) which causes material to move as convection cells.  Majority of this evidence was discovered during ocean floor exploration and the question wegener failed to answer was explained by a scientist named Arthur Holmes.  Mantle material moves up at ridges and move away in opposite directions moving the continents. In cooler areas beneath trenches, mantle material sinks causing oceanic crust to descend into the mantle and be recycled.

5. Theory of Continental Drift 1)225 Million years ago, supercontinent called Pangaea. Main Points of Continental Drift Theory Include: 2)200 Million years ago, supercontinent split to form two main land masses. Laurasia in the north and Gondwanaland in the south. 3)Laurasia consisted of; Asia, Europe, and North America. 4)Gondwanaland consisted of; Africa, Australia, Antarctica, South America, and India. 5)Over the past 150 million years, these land masses split and drifted to their present positions.