Question
Which of these pieces of evidence did Alfred Wagner site to support his hypothesis that continental drift?
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Alfred Wegener cited the following pieces of evidence to support his hypothesis of continental drift:
1. Jigsaw Puzzle Fit: Wegener noticed that the continents on the map could easily fit together like pieces of a puzzle. He specifically noted the similarity in the coastlines of South America and Africa, suggesting that they were once connected.
2. Fossil Distribution: He observed that identical fossils of plants and animals were found on opposite sides of the Atlantic Ocean, such as the presence of Mesosaurus fossils in both South America and Africa. This indicated that the continents were once joined and later separated.
3. Rock Sequences and Mountain Ranges: Wegener found that similar rock formations and geological structures were present on different continents that were geographically far apart. For instance, the Appalachian Mountains in North America aligned with the Caledonian Mountains in Europe. He argued that these mountains were once part of the same ancient mountain range that split apart as the continents moved.
4. Paleoclimate Evidence: Wegener studied evidence of ancient climates and found that certain regions, which are presently far away from the equator, showed signs of glaciation and the presence of coal beds. For example, glacial striations were found in Brazil and coal deposits were discovered in Antarctica. These findings suggested that these regions were once in different locations, closer to the polar regions.
5. Seafloor Spreading: While not directly proposed by Wegener himself, the idea of seafloor spreading emerged as evidence to support continental drift. Later research revealed the presence of mid-ocean ridges and the symmetrical magnetism patterns recorded in seafloor rocks, indicating that the ocean floor was spreading apart at these ridges and pushing the continents away.
It is important to note that while Wegener's hypotheses were widely disregarded during his time, these pieces of evidence became a foundation for the development of plate tectonics theory, which is now widely accepted in modern geology.
1. Jigsaw Puzzle Fit: Wegener noticed that the continents on the map could easily fit together like pieces of a puzzle. He specifically noted the similarity in the coastlines of South America and Africa, suggesting that they were once connected.
2. Fossil Distribution: He observed that identical fossils of plants and animals were found on opposite sides of the Atlantic Ocean, such as the presence of Mesosaurus fossils in both South America and Africa. This indicated that the continents were once joined and later separated.
3. Rock Sequences and Mountain Ranges: Wegener found that similar rock formations and geological structures were present on different continents that were geographically far apart. For instance, the Appalachian Mountains in North America aligned with the Caledonian Mountains in Europe. He argued that these mountains were once part of the same ancient mountain range that split apart as the continents moved.
4. Paleoclimate Evidence: Wegener studied evidence of ancient climates and found that certain regions, which are presently far away from the equator, showed signs of glaciation and the presence of coal beds. For example, glacial striations were found in Brazil and coal deposits were discovered in Antarctica. These findings suggested that these regions were once in different locations, closer to the polar regions.
5. Seafloor Spreading: While not directly proposed by Wegener himself, the idea of seafloor spreading emerged as evidence to support continental drift. Later research revealed the presence of mid-ocean ridges and the symmetrical magnetism patterns recorded in seafloor rocks, indicating that the ocean floor was spreading apart at these ridges and pushing the continents away.
It is important to note that while Wegener's hypotheses were widely disregarded during his time, these pieces of evidence became a foundation for the development of plate tectonics theory, which is now widely accepted in modern geology.
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