Intro to Continental Drift
Alfred Wegener
When you look at a map of Earth’s surface, you see that the edges of the continents look as if they would fit together like a puzzle. A meteorologist named Alfred Wegener thought that the fit of the continents wasn’t just a coincidence. He believed that all the continents were once joined together at some point in the past. In the early 1900’s, Wegener proposed the idea of continental drift. The continental drift hypothesis states that continents have moved around the Earth to reach their current locations. This idea was revolutionary and started a new science about how the Earth's surface changes over time.
When you look at a map of Earth’s surface, you see that the edges of the continents look as if they would fit together like a puzzle. A meteorologist named Alfred Wegener thought that the fit of the continents wasn’t just a coincidence. He believed that all the continents were once joined together at some point in the past. In the early 1900’s, Wegener proposed the idea of continental drift. The continental drift hypothesis states that continents have moved around the Earth to reach their current locations. This idea was revolutionary and started a new science about how the Earth's surface changes over time.
Evidence that continents have moved
1. Continental Jigsaw Puzzle
Wegener believed that all continents were once connected in one large landmass called Pangaea. When looking at maps he noticed that the edges of the continents fit together like puzzle pieces (look at the picture above) showing that they were once together. When the continents broke apart, they “drifted” to their present locations. Watch the video below to see how the continents moved over time.
Wegener believed that all continents were once connected in one large landmass called Pangaea. When looking at maps he noticed that the edges of the continents fit together like puzzle pieces (look at the picture above) showing that they were once together. When the continents broke apart, they “drifted” to their present locations. Watch the video below to see how the continents moved over time.
2. Fossil Evidence
Fossil remains of the same animals have been found in areas that are currently separated by large distances. For example, fossils of the reptile Mesosaurus have been found in South America and Africa. This swimming reptile lived in fresh water and on land. How could fossils of Mesosaurus be found so far apart? It is very unlikely that it could have traveled between the continents as they are today. Wegener thought this reptile lived on both continents when they were connected.
Fossil remains of the same animals have been found in areas that are currently separated by large distances. For example, fossils of the reptile Mesosaurus have been found in South America and Africa. This swimming reptile lived in fresh water and on land. How could fossils of Mesosaurus be found so far apart? It is very unlikely that it could have traveled between the continents as they are today. Wegener thought this reptile lived on both continents when they were connected.
3. Climate Evidence
Fossils of warm weather plants were found on the island of Spitzbergen in the Arctic Ocean. Wegener believed that this island drifted from a tropical region to its current location. Also, glacial deposits and grooved bedrock found in southern areas of South America, Africa, India, and Australia indicate that these warm areas were once covered by glaciers. Wegener believed that these continents were once covered with ice near Earth’s South Pole and then moved to their current locations.
Click the links below to observe the location and glaciation of South America, Africa, India andAustralia 250 million years ago.
Fossils of warm weather plants were found on the island of Spitzbergen in the Arctic Ocean. Wegener believed that this island drifted from a tropical region to its current location. Also, glacial deposits and grooved bedrock found in southern areas of South America, Africa, India, and Australia indicate that these warm areas were once covered by glaciers. Wegener believed that these continents were once covered with ice near Earth’s South Pole and then moved to their current locations.
Click the links below to observe the location and glaciation of South America, Africa, India andAustralia 250 million years ago.
4. Rock Evidence
If the continents were connected at one time, then rocks that make up the continents should show similarities. Similar rock structures are found on different continents. For example, parts of the Appalachian Mountains of the eastern United States are similar to those found in Greenland, Western Europe, and Africa. These mountains formed when North America collided with Europe and Africa as the continents drifted together. Look at the image below to see where these mountains were during the time of Pangaea.
If the continents were connected at one time, then rocks that make up the continents should show similarities. Similar rock structures are found on different continents. For example, parts of the Appalachian Mountains of the eastern United States are similar to those found in Greenland, Western Europe, and Africa. These mountains formed when North America collided with Europe and Africa as the continents drifted together. Look at the image below to see where these mountains were during the time of Pangaea.
the mechanism???
Although Wegener provided evidence to support his theory of continental drift, he couldn’t explain how, when, or why these changes in the position of the continents had taken place. Later, after Wegener’s death, more clues were found and new ideas related to continental drift were developed. One of these new ideas, seafloor spreading, helped to provide an explanation of how the continents could move and eventually led to the Theory of Plate Tectonics. Watch more about this in the video below.