How did the continental plateau come about

plate tectonics

But what was the reason for this almost unanimous and violent resistance to Wegener and his theory? After all, he was not only able to explain the astonishing biogeographical similarities between the continents, but also offered a much-needed explanation for the formation of mountains in the interior of continents such as the Urals or the Himalayas.

Wegener postulated that the Urals were remnants of a long-ago continental collision, whereas the tectonically active Himalayas were the result of a relatively recent collision. Today this is a natural and catchy idea, but in Wegener's time it caused a scandal.

Wegener wasn't the first to notice the amazingly good fit of the coasts of South America and Africa. © NOAA

Theory with no plausible mechanism

This storm of protest and resistance was all the more astonishing as the idea of ​​continents in motion was by no means new: the Dutch cartographer Abraham Ortelius had already suggested in 1596 that America had been torn away from Europe and Africa by "earthquakes and floods" and continued : "The traces of these cracks are revealed when you look at a map of the world and compare the coasts of the three continents."

So what was so scandalous about Wegener's theory? One of Wegener's problems was that although his theory offered a plausible explanation for a whole range of phenomena in the history of the earth, it was on the other hand on feet of clay: “At that time, Wegener could not name any forces or mechanisms that would have been sufficient to shift the continents to accomplish, ”explains the science historian Reinhard Krause from the Alfred Wegener Institute. Wegener himself was well aware of this deficiency, but he did not doubt the fundamental correctness of his theses.

Watt at low tide © Green oval

Tidal force as the engine of plate movement?

Wegener assumed that the lighter continents floated on a layer of denser material and could “plow through” it like icebergs through thin pack ice. Wegener could only name differences in centrifugal force and the tides as the motors for this movement - forces that were far too weak to have such a disruptive effect.

At the time, a scientist calculated that a tidal force strong enough to move entire continents would bring the earth's rotation to a standstill in less than a year. Opponents also criticized that plowing the continents through the oceanic crust, as suggested by Wegener, would have deformed the continents beyond recognition.

On the Mid-Atlantic Ridge, the tectonic plates drift apart by around 2 centimeters per year. © USGS

Calculation error in the migration speed

Another weak point of Wegener's theory was the time frame he set for the hike. Due to errors in his original data, he concluded in his calculations that North America and Europe are drifting apart by more than 250 centimeters per year - more than ten times the fastest plate movement known today and more than 100 times the actual migration speed of both plates.

But despite all the weaknesses in parts of his theory, what Wegener presented to geoscientists in lectures and in 1915 in his book "The Origin of the Continents and Oceans" was a visionary and groundbreaking idea. Even if the majority of the scientists rejected the ideas as not to be taken seriously, there were some researchers who supported Wegener and themselves began to look for clues to the migration of the continents….

Nadja Podbregar
Status: 02/21/2001