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Alfred Wegener: The Concept Of The Continental Drift
As far back in 1910, the concept of the continental drift was first recognised by Alfred Wegener, when he considered the map of the world, under the direct impression produced by the congruence of the coastlines on either side of the Atlantic. At first, Wegener did not may much attention to the idea as he regarded it as 'improbable'. One of the reasons for this was because there was no evidence to support this idea, only logic, therefore the idea seemed pointless and far-fetched. -
The First Piece Of Evidence Which Sparked An Idea
Alfred obtained a report which consisted of paleontological evidence for a former land bridge between Brazil and Africa. Wegener researched in the fields of geology and palaeontology, which collectively provided him with the information to pursue his research. Knowledgeable in both fields, he concluded that the theory that the 'position of the continents had never altered' was incorrect, meaning the continents had shifted, and that South America and Africa which were once attached, broke apart. -
Wegener Publishes His Controversial Hypothesis
Wegener published his hypothesis of the continental drift in his revolutionary book. Whilst he was not the first to observe that certain continental coastlines fit together, he drew on a broader range of disciplines, which attracted the attention of many scientists. His hypothesis proposed that Earth’s continents had once been connected but had moved slowly apart over millions of years. He based his argument on evidence, matching coastlines of continents by the similarity of fossils and rocks. -
Evidence Of Fossil Distribution
When Wegener proposed his continental drift hypothesis, he knew that similar fossil remains had been found on different continents, meaning that their plates must have once been connected. This was an example of a piece of evidence Wegener built his theory upon. It was this evidence and a diverse range of disciplines which captured the attention of other scientists, ultimately leading to the acception of his theory. -
Responses To Wegener's Hypothesis
By 1923, there had already been many responses to Wegener's theory, most of them dismissing the theory due to its many flaws, as he failed to provide evidence for how the continents moved. Yet still, others thought that his idea was important, however, needed to be further explored. -
The Importance Of Paleomagnetism - New Evidence
For several decades, little research was written on Alfred's controversial theory. However, in 1950, a newly developed field of paleomagnetism (the study of Earth’s magnetic field) proved that the continents had once been positioned differently by uncovering certain minerals known to form in alignment with Earth’s polarity. But until an adequate mechanism to move the continents was found, many scientists remained unconvinced and did not pursue any reasearch on the theory. -
Harry Hess and Sea Floor Spreading - More Evidence
In 1959, geology professor Harry Hess wrote a paper explaining a process he called seafloor spreading, where 'molten rock seeps up from the Earth’s interior through mid-ocean ridges (undersea mountain chains), spreads out to create new ocean floor, and then sinks back into the Earth’s interior through oceanic trenches.' This would prove to be the mechanism for continental drift that scientists had been looking for. Seafloor spreading made continental drift a plausible idea. -
More Hypotheses About The Continental Drift
Hess also encountered controversy to his hypothesis because data was scarce at the time. This changed when Paleomagnetists discovered that Earth’s magnetic field sometimes flips its orientation, meaning that in the past a compass needle would have pointed south instead of north. This led geophysicists to propose the Vine-Matthews- Morley hypothesis in 1963: If new oceanic floor is continually being created at mid-ocean ridges, ocean-floor rocks should record past reversals of the magnetic field. -
Confirmation Of The Sea Floor Spreading Hypothesis
Subsequent research by geophysicist Walter C. Pitman confirmed the Vine-Matthews-Morley hypothesis. Pitman studied the magnetic orientation of the ocean floor on either side of the Pacific- Antarctic Ridge. The black stripes represent parts of the seafloor that formed when the orientation of Earth’s magnetic field was “normal” and the white stripes represent parts of the seafloor that formed when the magnetic field was “reversed.” The pattern confirms the seafloor- spreading hypothesis. -
Acceptance Of The Continental Drift
Confirmation of the Vine-Matthews-Morley hypothesis proved that the seafloor spreads as Hess had claimed. This helped validate Wegener’s continental drift hypothesis. As new evidence arose, theories were accepted as facts. Many scientists published articles stating their approval of the theory: "Moving plates, like evolving species, have become accepted as fact." - Henry Frankel.
