the continental shift theory and weneger

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Wegener and Continental Drift Theory

How we interpret the science of centuries past cannot be separated from our view of

modern science. The danger is that this view may be based on a stereotype. A commonstereotype of a scientist is that of a rational professional that evaluates new ideas based

only on an objective evaluation of data. This would leave the impression that, unlikeearly scientists, modern scientists proposing radical new ideas do not need to fear thereactions of those entrenched in the existing system. Alfred Wegener is one modern

scientist amongst many that demonstrate that new ideas threaten the establishment,

regardless of the century.

Alfred Wegener was the scientist who championed the Continental Drift Theory throughthe first few decades of the twentieth century. Simply put, his hypothesis proposed that

the continents had once been joined, and over time had drifted apart. The jigsaw fit that

the continents make with each other can be seen by looking at any world map. The image below shows the continents of Africa and South America joined together. Clicking on the

image will illustrate their drift to their current positions (thanks are due NASA for theoriginal images).

Wegener and his Critics

Since his ideas challenged scientists in geology, geophysics, zoogeography and

paleontology, it demonstrates the reactions of different communities of scientists. The

reactions by the leading authorities in the different disciplines was so strong and sonegative that serious discussion of the concept stopped. One noted scientist, the geologist

Barry Willis, seemed to be speaking for the rest when he said:

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

students.

Barry Willis's and the other scientists wishes were fulfilled. Discussion did stop in the

larger scientific community and students' minds were not befogged. The world had to

wait until the 1960's for a wide discussion of the Continental Drift Theory to be restarted.

Why did Alfred Wegener's work produce such a reaction? He was much more diplomaticin presenting his theory than Galileo. Although he believed himself to be right and that

some of his arguments were compelling, he knew he would need more support toconvince others. His immediate goal was to have the concept openly discussed. Wegener did not even present Continental Drift as a proven theory. These modest goals did not

spare him. The fact that his work crossed disciplines exposed him to the territoriality of

scientific disciplines. The authorities in the various disciplines attacked him as aninterloper 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 established authorities in

each of the disciplines.



One can't underestimate the effect of a radical new viewpoint on those established in a

discipline. The authorities in these fields are authorities because of their knowledge of thecurrent view of their discipline. A radical new view on their discipline could be a threatto their own authority. One of Alfred Wegener's critics, the geologist R. Thomas

Chamberlain, could not have summarized this threat any better :

"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.

Continental Drift

Theory:Building the Case

In spite of the criticisms from several different disciplines Wegener was able to keep

Continental Drift part of the discussion until his death. He knew that any argument basedsimply on the jigsaw fit of the continents could easily be explained away as a

coincidence. 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 Africawould 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 SouthAmerica, and another in Antartica, India and central Africa) [_1_] . The graphic below

shows the striking distribution of fossils on the different continents.

http://showannotation%28references%2C1-1%29/




Wegener used an Alexander duToit graphic to demonstrate the uncanny match of geology

between eastern South

America and westernAfrica.

Continental Drift

Theory:The

Fatal Flaw

Thus far the picture painted

of Alfred Wegener'scontemporaries is not

flattering. But this might be

unfair. One would expectsome scientists to resist

ideas that would invalidate

their life's work. But itdoesn't explain all criticism

of Wegener's ideas.

Wegener presented very

compelling arguments for Continental Drift but there

were alternate explanations

for some of his

observations. To explainthe unusual distribution of

fossils in the SouthernHemisphere some scientists proposed there may once have been a network of land

bridges between the different continents. To explain the existence of fossils of temperate

species being found in arctic regions, the existence of warm water currents was proposed.Modern scientists would look at these explanations as even less credible than those

proposed by Wegener, but they did help to preserve the steady state theory.

New theories donot always arrive with all the t's crossed and i's dotted. Wegener did not

have an explanation for how continental drift could have occurred. He proposed two

different mechanisms for this drift, one based on the centrifugal force caused by therotation of the earth and a 'tidal argument' based on the tidal attraction of the sun and the

moon. These explanations could easily be proven inadequate and opened Wegener to

ridicule because they were orders of magnitude too weak. Wegener really did not believethat he had the explanation for the mechanism, but that this should not stop discussion of

a hypothesis. The scientists of the time disagreed. After Alfred Wegener died, the

Continental Drift Theory was quietly swept under the rug. With the Continental Drift



Theory out of the way, the existing theories of continent formation were able to survive,

with little challenge until the 1960's.

Wegener and Darwin

The main problem with Wegener's hypothesis of Continental Drift was the lack of amechanism. He did not have an explanation for how the continents moved. Some argue

that this failing justified the early reactions to his work and to its dismissal. But Charles

Darwin was missing a mechanism for the inheritance of beneficial traits when he published the Origin of Species in 1859. Darwin had amassed a huge amount of evidence

that supported some type of adaptive process that contributed to the evolution of new

species, much like Wegener had for Continental Drift. He argued that with the naturalvariations 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 newspecies. One major flaw in Darwin's theory was that he did not have a mechanism for

how the traits could be preserved over the succeeding generations. At the time, the prevailing theory of inheritance was that the traits of the parents were blended in the

offspring. But this would mean that any beneficial trait would be diluted out of the 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.

In spite of the lack of a mechanism for the preservation of traits, Darwin's theory quickly

came to dominate. Within 5 years, Oxford University was using a biology textbook thatdiscussed biology in the context of evolution by natural selection. The textbook stated,

"Though evidence might be required to show that natural selection accounts for

everything ascribed to it, yet no evidence is required to show that natural selection has

always been going on, is going on now, and must ever continue to go on. Recognizingthis is an a priori certainty, let us contemplate it under its two distinct aspects." At

Oxford, evolution by natural selection had gone from hypothesis to a priori certainty inthe space of 5 years. In this case the scientific community (excepting a minority of

skeptics) chose to ignore the lack of mechanism. Wegener had no such luck with his

Continental Drift Theory. [_2_] .

The mechanism necessary to explain the preservation of beneficial traits was publishedshortly after the Origin of Species. Unfortunately it was largely ignored. In 1865, an

obscure Augustinian monk from Moldavia presented a paper to the Natural History

Society of Brunn where he discussed the results of experiments on pea plants. The results

presented by this monk, Gregor Mendel, pointed to traits being inherited 'whole' (alsoknown as particulate inheritance), and that certain traits (recessive traits) that disappear in

one generation can reappear in a following generation (see Saving Darwin). This would

have gone a long way in plugging at least one hole in the Darwin's theory. Mendel's work was largely ignored until about 1900. Shortly afterward it was incorporated into our

modern view of evolution by natural selection known as the 'modern synthesis'. About 2

years before his death, Darwin received a book on hybridization by Focke that discussed


http://www.scientus.org/Mendel-Darwin.html


http://www.scientus.org/Mendel-Darwin.html



the monk's work. It is known that Darwin never read the pages from Focke that discussed

Mendel's work.

Darwins theory had another problem. His theory proposed a gradual evolution throughsuccessive generations. But the fossil record at the time didn't co-operate. There seemed

to be a 'explosion' of different life-forms over a relatively short time span (in geologicterms) in the early Cambrian period. There also didn't seem to be any transitional forms

of life preceding these species. This eventually became known as the Cambrian

Explosion. Darwin himself recognized this as a serious issue with his theory and he

discussed it in the Origin of Species. Darwin explained away the problem as a problem

with the fossil record and not with his theory. Over the course of the twentieth century, amuch better picture of the fossil record of both the Cambrian and Pre-Cambrian eras was

developed. The new discoveries made the problem worse. Much worse. In the early

twentieth century, the American paleontologist, Charles Walcott, discovered andexcavated the Burgess Shale in British Columbia, Canada. He found 65,000 more

specimens of early Cambrian life, many of which were complex multi-celled animals. At

the time there still was no evidence of transitional forms in the pre-Cambrian. Onlyrecently have they started discovering isolated examples of moderately complex multi-celled animals from the Pre-Cambrian. This still doesn't explain the step-change in the

diversity of life-forms in the Cambrian.

Wegener and Galileo

Wegener also shares much in common with Galileo. Wegener probably had at least asstrong a case for Continental Drift in 1929 as Galileo had for the Copernican model in

1633. The reason many do not realize this is that the controversy is usually presented as a

controversy between Galileo and the Church and not Galileo and other scientists (see

Galileo's Battle for the Heavens). As a result most discussions of the early CopernicanModel do not even mention any problems associated with the Copernican model. But it

was a scientific controversy and it had many of the same elements of the ContinentalDrift controversy.

Galileo had his own 'tidal argument' ; one that was even more embarassing than

Wegener's. Galileo argued that the tides were caused by the sun. It is difficult to

understand how a great scientist who had spent his youth less than 20 kilometres from thesea would present an argument for Copernicism based on there only being 1 tide per day

and where the tides cycle over the year and not over a month. While it took a noted

geologist to show that Wegener's tidal argument was ridiculous, Galileo's tidal argument

could be challenged by any fisherman or coastal dweller.

The tidal argument wasn't the only or the major problem with Galileo's defense of

Copernicism. Wegener's critics never presented strong arguments that Continental Drift

couldn't have happened or that it wasn't happening. They did show that the mechanism

that Wegener suggested was driving Continental Drift was inadequate. The scientists of

Galileo's day did have scientifically valid reasons to doubt a moving earth. A moving

earth required that a phenomenon known as stellar parallax (see Copernicism and Stellar

http://www.scientus.org/Galileo-Battle-for-Heavens.html

http://www.scientus.org/Copernicus-Stellar-Parallax.html


http://www.scientus.org/Galileo-Battle-for-Heavens.html




Parallax) would be observed . No one in Galileo's day or for two centuries after his death

was able to observe this phenomenon.

Another argument against Copernicism was very simple and in its own way, empirical. In1551, only 8 years after Copernicus's death, the Prutenic tables were developed from the

Copernican model to predict the positions of stars and planets. There was 80 years of experience in comparing the performance of Copernican-based tables (Prutenic) and

Ptolemaic-based tables (Alphonsine). It didn't seem that one was much better than theother. A reasonable conclusion based on this experience is that if the Ptolemaic was

wrong, then the Copernican was not right. These scientists did not have computers and

advanced statistical techniques to meticulously compare the predictions of the twosystems. When these tools arrived in the twentieth century their hunch was proven

correct; there wasn't much separating the two systems [_3_] . Today, it is the Keplerian

system of planetary motion that is taught in schools, not the Copernican or the Ptolemaic.Galileo knew of Kepler's model and had never accepted it during his lifetime.

Science:A Question of Faith

Science depends on facts. It also depends on reason. But fact and reason alone cannot

explain the different reactions to new hypotheses and theories we see in the examplesabove. They all had some compelling support and some serious shortcomings. Part of the

answer may lie in the sociology of groups. Another part lies in simple faith: faith that

future scientists will address the shortcomings in the initial theories. With Darwin's

theory, the community of scientists were willing to accept the theory based on a faith thatthe problems with inheritance and the Cambrian Explosion would be dealt with by future

scientists. With Wegener, the community of scientists simply did not have the faith that a

mechanism would be found to explain the movement of land masses. With Galileo, some

had faith that discovering stellar parallax was only a matter of time and others did not.But it is not only the community that requires faith, the champions of these new theories

require faith in their ideas, even when facts sometimes contradict their hypotheses. Ineach case above, there were facts which when combined with the current assumptions of

the time clearly contradicted their hypotheses. None of these scientists let those facts

deter them. Paul Feyerabend, a modern philosopher of science, presents a similar view,where he argues that science sometimes is required to work "against the facts". One of his

key examples, was how the heliocentric universe made less sense than a geocentric

universe during Galileo's day given the facts that were available at the time. Given the

current controversy over science versus religion, it is amusing that in the early stages of the development of many theories, science is dependent on faith much like religion.






the continental shift theory and weneger

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