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Questions and Answers
What was the name given by Alfred Wegener to the large land mass that formed when the continents collided?
What was the title of the book written by Alfred Wegener in 1915 that presented his ideas on continental drift?
Why did Alfred Wegener's hypothesis receive a lot of criticism?
What was one of the key pieces of evidence that supported Alfred Wegener's theory of continental drift?
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What was the name given by Alfred Wegener to the huge ocean that surrounded Pangaea?
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What was the major improvement made by Sir Edward Bullard and his colleagues to Wegener's idea?
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What is the primary location where divergent boundaries are found?
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What is the process that occurs at convergent boundaries?
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What is the characteristic of transform boundaries?
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What are areas of intense volcanic activity that remain in more or less the same location?
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Study Notes
Alfred Wegener's Theory of Continental Drift
- Alfred Wegener noticed that the continents looked like broken pieces of a puzzle in 1910 and proposed the theory of continental drift in 1915.
- He believed that the continents were drifting across the globe, but other scientists criticized him for lacking proof.
Wegener's Evidence
- Wegener's hypothesis was based on the idea that the continents fit together like pieces of a jigsaw, as seen on reasonably accurate world maps.
- He suggested that during the geologic past, the continents collided to form a large landmass called Pangaea, surrounded by a huge ocean called Panthalassa.
- Panthalassa included several smaller seas, including the Tethys Sea.
- Wegener's evidence indicated that as Pangaea began to split apart, the continents started to drift toward their present geographic positions.
Devising an Experiment
- Wegener attempted to match the shorelines of different continents to support his hypothesis, finding that some continents, like South America and Africa, seemed to fit together like pieces of a puzzle.
- In the 1960s, Sir Edward Bullard and his colleagues used a computer program to revisit Wegener's idea, allowing for more precise measurements and calculations.
- They used data from the ocean floor contours at a depth of 2000 meters (6560 feet) below sea level, which represents the true continental margins, to achieve a better fit between the continents.
Conclusion
- Wegener's initial attempt at matching the shorelines of continents provided valuable insights but was limited by the knowledge and technology of his time.
- The refinement by Bullard and his associates provided strong evidence supporting Wegener's theory of continental drift.
- This work laid the groundwork for the development of the modern theory of plate tectonics, which explains the movement of Earth's lithospheric plates and the formation of various geological features.
Plate Boundaries
- There are three types of plate boundaries:
- Divergent boundaries: found along oceanic ridges where new lithosphere is being added.
- Convergent boundaries: found where plates are moving together and one plate subducts beneath the other.
- Transform boundaries: found where lithospheric plates slowly grind past one another.
Hotspot
- A hotspot is an area of intense volcanic activity that remains in more or less the same location over a long period of time.
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Description
Learn about Alfred Wegener's 1915 theory of continental drift, where he proposed that continents move across the globe, and the challenges he faced from other scientists.
