4. Have you ever stared at a map of the world and thought why it looks like this? If you have, you are not alone.
A Brave Guess
In the late 1800s, a scientist named Alfred Wegener was interested in studying the map. He came up with a brave guess. He thought that all the continents once formed one huge land. A single large ocean was around this super-continent.
Floating "Ships"
Why do the continents look this way? Scientists believe that natural forces under the earth make the continents move and form the lands and oceans this way.
Over many centuries, slowly, the super-continent broke into two continents. One of them began to move to the north. Then it broke again, forming North America, Europe, and Asia. The gap between North America and Europe became part of the Atlantic Ocean. The second continent also broke apart to form South America, Africa, Australia, and Antarctica. The continents were like
floating ships at sea, moving to where they are nowadays.
Finding Evidence
It sounds unbelievable, but scientists have found evidence to support the guess. Firstly, it is the fossils. Ancient plants and animals of the same type were discovered both in South America and in Africa. Did they develop at the same time in two faraway places? It seems unlikely. Biologists believe that there must have been land bridges or other land connections that are unseen now.
The coastlines of the continents also seem to fit together. The east coast of South America can fit into the lower west coast of Africa. The east coast of North America matches parts of Africa's and Europe's coasts. It seems as if they fit together like pieces of a jigsaw puzzle (拼图).
Mountain rocks help explain the truth, too. Scientists has recognized a mountain chain that is more than four hundred million years old. It runs down the eastern part of Greenland and western Norway. Then it goes through northwest Scotland and Ireland before it reaches western Canada. Finally, it finds its way to northwest Africa.