The document discusses the theory of continental drift proposed by Alfred Wegener in 1915. It describes his hypothesis that all the continents were once joined together in a supercontinent called Pangaea, which began breaking apart around 200 million years ago. As the continents drifted apart, they formed the landmasses that exist today. The document also provides background on the Bering Land Bridge that connected Asia and North America during the last ice age, allowing humans, plants and animals to migrate between the continents.