Alfred Wegener's Continental Drift Theory

In 1912, Alfred Wegener proposed a theory that the continents had once been joined, and over time had drifted apart. This was the Continental Drift Theory. The reaction to Alfred Wegener's theory tells us much about the workings of science. We are taught that modern scientists are driven only by reason and facts. Only early scientists like Galileo needed to fear the reaction to their radical views. Neither of these beliefs is true. New ideas threaten the establishment, regardless of the century.

You can see why Wegener suspected that the continents had once been joined. The continents seem to have a jigsaw fit. The map of soil types below (derived from here) allows you to drag and rotate South America. See how well it fits with Africa. Wegener used this and several other arguments to build his case.

Wegener's theory drew from geology, geophysics, zoogeography and paleontology. It also drew the wrath of scientists from these disciplines. These reactions eventually shut down serious discussion of the concept. The geologist Barry Willis summed it up best:

further discussion of it merely incumbers the literature and befogs the mind of fellow students.

Wegener's only goal was to have the concept openly discussed. Alfred Wegener did not even present Continental Drift as a proven theory. What caused the extreme reaction? His work crossed disciplines. The authorities in the various disciplines attacked him as an amateur that did not fully grasp their own subject. More importantly however, was that even the possibility of Continental Drift was a huge threat to the authorities in each of the disciplines.

Radical viewpoints threaten the authorities in a discipline. Authorities are expert in the current view of their discipline. A radical view could even force experts to start over again. One of Alfred Wegener's critics, the geologist R. Thomas Chamberlain, suggested just that :

"If we are to believe in Wegener's hypothesis we must forget everything which has been learned in the past 70 years and start all over again."

He was right.

Wegener was able to keep the discussion of Continental Drift alive until his death. He knew that any argument based simply on the jigsaw fit of the continents could easily be explained away. To strengthen his case he drew from the fields of geology, geography, biology and paleontology. Wegener questioned why coal deposits, commonly associated with tropical climates, would be found near the North Pole and why the plains of Africa would show evidence of glaciation. Wegener also presented examples where fossils of exactly the same prehistoric species were distributed where you would expect them to be if there had been Continental Drift (e.g. one species occurred in western Africa and South America, and another in Antartica, India and central Africa) [_1_] . The graphic below shows the striking distribution of fossils on the different continents.

Wegener used an Alexander duToit graphic to demonstrate the uncanny match of geology between eastern South America and western Africa.

The picture painted of Alfred Wegener's contemporaries might not be fair. An attachment to the status quo doesn't explain all of the criticism. There were alternatives. To explain the unusual distribution of fossils in the Southern Hemisphere, critics proposed a network of land bridges connecting the different continents. To explain fossils of temperate species being found in arctic regions, critics suggested warm water currents. Today these explanations might seem less credible than those proposed by Wegener but they did help to preserve the steady state theory.

New theories often have rough edges. Alfred Wegener proposed two different mechanisms for continental drift. One was based on the centrifugal force caused by the rotation of the earth and another a 'tidal argument' based on the tidal attraction of the sun and the moon. These explanations could easily be proven inadequate. They opened Wegener to ridicule because they were orders of magnitude too weak. Wegener knew he didn't have a mechanism, but believed the evidence should allow continued discussion of the hypothesis. Wegener's contemporaries disagreed. A conference was held by the American Association of Petroleum Geologists in 1926 that was critical of the theory. Alfred Wegener died a few years later. With his death, the Continental Drift Theory was quietly swept under the rug. The existing theories of continent formation were allowed to survive, with little challenge until the 1960's.

The main problem with Wegener's hypothesis of Continental Drift was the lack of a mechanism. He did not have an explanation for how the continents moved. His attempt to explain it using tides only made things worse. But both Galileo and Darwin had serious flaws in their theories when they were first presented. Galileo had a tidal theory that was more embarassing than Wegener's. Darwin was missing a mechanism for how beneficial traits could survive over generations. History treats the three men quite differently.

In the Origin of Species, Charles Darwin argued that with the natural variations that occur in populations, any trait that is beneficial would make that individual more likely to survive and pass on the trait to the next generation. If enough of these selections occured on different beneficial traits you could end up with completely new species. He did not have a mechanism for how the traits could be preserved over the succeeding generations. At the time it was thought that the traits of the parents were blended in the offspring. Unfortunately, blending would dilute any beneficial trait out of a population within a few generations. This is because most of the blending over the next generations would be with individuals that did not have the trait. This flaw didn't stop universities such as Oxford from teaching Evolution as fact shortly after the publication of the Origin of Species. This hole in Darwin's theory was plugged about 50 years later using the work of a Roman Catholic monk, Gregor Mendel. Mendel proposed an alternative to blending where traits were inherited whole (see Mendel and Darwin).

Darwin's theory had another problem. His theory proposed a gradual evolution through successive generations. The fossil record of the time contradicted this. There seemed to be an 'explosion' of different life-forms over a relatively short time span in the early Cambrian period ( the Cambrian Explosion). There didn't seem to be any transitional forms of life preceding these species. New discoveries made the problem worse. Much worse. In 1909, a massive find of 65,000 more specimens of early Cambrian life was discovered in the Burgess Shale in British Columbia, Canada. Many were complex multi-celled animals with no evidence of preceding transitional forms.

Alfred Wegener also shares much in common with Galileo. Galileo had his own 'tidal argument' ; one that was even more embarassing than Wegener's. To defend his belief that the sun was the center of the solar system, he argued that the tides were caused by the sun. His argument was based on there only being 1 tide per day and where the tides cycle over the year and not over a month. It didn't take a scientist to realize that his argument was ridiculous.

There were other problems with Galileo's defense of Copernicism. The scientists of the time had scientifically valid reasons to doubt a moving earth. A moving earth required that a phenomenon known as stellar parallax would be observed (see Copernicism and Stellar Parallax). It would not be observed until two centuries after Galileo's death. Neither did the current data support the Copernican Model. Modern statistical analyses don't either [_2_] . Galileo wasn't proposing Kepler's model; he was proposing the Copernican Model against the Keplerian and other models. More info can be found at Galileo's Battle for the Heavens and The Galileo Myths.

Why was one theory quickly accepted, another quickly dismissed, and the other a cause of controversy. All of the theories had serious flaws. The answer might be sociological not scientific.

Darwin was an insider in English scientific circles. His grandfather, Erasmus, was an early student of evolution and his half-cousin, Francis Galton, was a famous statistician. Being part of the Wedgewood-Darwin clan meant he would never have to worry about money. His connections meant that he could enlist the elite of mid-nineteenth century English science if needed. The most famous of the early defenses of Darwinism was not by Darwin himself but by the famous biologist, Thomas Huxley and the social philosopher, Herbert Spencer. Darwin's ideas were adopted by supporters of laissez-faire capitalism. "Survival of the fittest" gave an ethical dimension to the no-holds barred capitalism of the late nineteenth century.

Alfred Wegener wasn't an insider. His few allies (duToit and Holmes) were no match for his many skeptics. His place of birth may have played a role, too. Anti-German bias was very strong in the 1910's and 1920's in English-speaking countries. This resulted in German-based names for cities, streets, foods and animal breeds being changed to names that were more 'patriotic'. Being German wasn't Wegener's only problem; the arguments he used to support his hypothesis crossed into disciplines that were not his specialty. He was trained as an astronomer and worked as a meterologist. He was considered an outsider for a reason.

The early history of the Copernican model demonstrates the effect of outside forces. The publication of Copernicus' de Revolutionibus drew more criticism in Protestant countries than Catholic countries. de Revolutionibus included a copy of the letter from the Vatican urging him to share his work, a dedication to the pope, and a thank you to a bishop who was an important supporter of his work. The Vatican's interest began 10 years before the publication of de Revolutionibus, after a series of lectures given to Pope Clement VII on Copernicus's work. The involvement of the church may have muted criticism from academics in the Catholic countries of Europe and encouraged criticism in the Protestant countries. The reverse happened after Galileo's trial in 1633. Galileo was tried for not obeying an order from 1616 to not teach the Copernican theory as a proven theory but only as a hypothesis (more on this at Galileo's Battle for the Heavens).

One irony missed by discussions of science and religion is how much both depend on faith. Darwin needed an explanation for the Cambrian Explosion and a mechanism for the preservation of traits (see Mendel and Darwin). Wegener needed a mechanism for Continental Drift. Galileo needed an explanation for the lack of stellar parallax and the poor performance of his model (see Galileo's Battle for the Heavens). It is not only the community that requires faith. The champions of these new theories require faith in their ideas, even when facts contradict their hypotheses. Paul Feyerabend, a modern philosopher of science, argues that science is sometimes required to work "against the facts". His example was how the heliocentric system made less sense than a geocentric system during Galileo's time. Faith is important to new scientific theories: faith that future scientists will address a theory's shortcomings.