Q:

What evidence is there of the continental drift theory?

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Quick Answer

According to National Geographic, sea floor spreading and plate tectonics indicate that the continents do move or shift, which supports continental drift theory. Fossils of the Mesosaurus, an ancient freshwater reptile found in the southern parts of South America and Africa, also indicate that the two continents could have once been one solid continent that drifted apart, since the reptile could not have swum across the ocean.

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Full Answer

Continental drift is a theory originally proposed by Alfred Wegener, who believed the continents were once one large continent known as Pangaea that later separated into several continents. One indication of this possibility is the appearance of the western African and eastern South American coasts, which look like two interlocking jigsaw puzzle pieces. Finding fossils of the Mesosaurus on the southern hemispheres of both continents is a further indication that the two continents were once together and later drifted apart.

Another indication of continental drift is tectonic activity and seafloor spreading. Scientists agree that continents rest on rocks called tectonic plates, which shift and move. Sea floor spreading further supports the continental drift theory. As molten rock rises from the Earth, it forms new crust between the plates. When this occurs, the sea floor grows wider, pushing the two continents apart. Sea floor spreading indicates that since the continents presently move apart, previous continental drift was possible and probable as well.

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Related Questions

  • Q:

    What is the theory of continental drift?

    A:

    The theory of plate tectonics, formerly known as continental drift, is a working model that describes the movement of the continents and sea floor across the surface of the Earth. The theory explains many anomalous facts about Earth's geology, such as the present arrangement of landmasses.

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  • Q:

    How does continental drift happen?

    A:

    Continents rest on massive plates known as tectonic plates, which are fluid and able to move due to the mantle and magma underneath, and as the tectonic plates move about, they cause continental drift to happen. The concept of continental drift was first described in the early 20th century by German scientist Alfred Wegener, who explained that continental landmasses were actually drifting across the Earth. This is opposed to the original theory that landmasses are fixed and immobile.

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  • Q:

    What five factors did Wegener use to support his theory?

    A:

    In proposing the theory of continental drift, Alfred Wegener relied on evidence from the shape of the continents, the distribution of plants and animals, similarities between landscapes, contiguous veins of ore that ran between continents, and the distribution of glacial deposits. Though the evidence for his hypothesis was strong, the theory lacked a mechanism and was not generally accepted during Wegener's lifetime.

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  • Q:

    What argument was used to dispute the theory of plate tectonics?

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    Andrew Alden of About explains that Australian geologist Sam Carey's theory of Earth expansion, the idea that the continents fit together properly only on a formerly smaller Earth, once rivaled the theory of plate tectonics. Carey's ideas expanded upon Wegener's continental-drift theory and hypothesised that the continents fit together properly on a shrunken Earth. From about the 1930s to the 1950s, this idea of Earth expansion remained a legitimate hypothesis.

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