In the early 1900's the German geographer and meteorologist Alfred Wegener came up with a hypothesis which stated that all of Earth's continents were once connected in to a single, huge landmass long ago and have since moved [or "drifted"] apart. Wegener was so sure this land existed he even named this supposed super-continent Pangaea, which means "one world" in Greek.
Wegener, being a good scientist, knew that a good acceptable theory needs supporting evidence, so he spent many years of his later adult life researching and traveling the world observing and accumulating some supporting data. He came up with the following.
- Certain continental coastlines fit together almost perfectly, especially Europe to North America, Africa to South America, and Arabia to Africa.
- Fossil remains of certain types of freshwater plants, and reptiles that could not swim, fly or float were found on continents worldwide separated by thousands of kilometers of ocean.
- Identical rock layers and geologic structures (like folded mountains) were found on both sides of an ocean. For example, the Appalachian Mountains in eastern Canada are made of the same rock layers and formations as the Caledonian Mountains of Scotland and Norway. This also occurs between the Brazilian Highlands of South America and the Central African highlands. Wegener even noticed there were folded mountains in the middle of continents, like the Ural Mountains that separate Europe from Asia, and this is highly unusual, as mountains are thought to form on the edges of continents.
- Evidence of past glaciers in places like Australia and South Africa
- Layers of coal, limestone, and salt in places like Canada, Siberia, and Antarctica