Under the Microscope/Dr William Reville: Alfred Lothar Wegener died in November 1930 on a meteorological expedition to Greenland, his bold theory of continental drift rejected by the scientific community.
Thirty years after his untimely death, at the age of 50, Wegener's ideas became the catalyst and framework for the development of plate tectonics, one of the most important of geological theories. Plate tectonics is as important to the earth sciences as the theory of evolution is to the life sciences.
Wegener was born in Berlin; in 1905, after being educated in Heidelberg and Innsbruck, he graduated from his city's university with a PhD in astronomy. He was also fascinated with the developing fields of meteorology and climatology and, over his career, made several key contributions. He did pioneering work on the use of balloons to track air circulation and wrote The Thermodynamics Of The Atmosphere, a textbook that became a standard reference throughout Germany. He also flew in hot-air balloons (and, in 1906, with his brother Kurt, broke the world endurance record by staying aloft for more than 52 hours).
Wegener took up a lectureship at the University of Marburg in 1908. He was drafted into the army in 1914 but was released from active duty after being wounded and served out the war in the army weather-forecasting service. While recuperating from his injuries, Wegener pondered a question that had intrigued him for many years. Why, when you examine a globe, do most of the continents seem to fit together like the pieces of a jigsaw puzzle? If moved westwards, for example, the coastline of west Africa fits neatly into the east coast of South America and the Caribbean Sea.
Wegener explained this striking fact by proposing that, 300 million years ago, all the continents were compressed into a single super-continent near the South Pole, which he called Pangea, from the Greek, meaning "all lands". Pangea split into the continents as we know them and drifted apart.
Wegener was not the first to suggest the continents had once been connected, but he was the first to support the proposal with extensive evidence. Fossils of identical plants and animals are found on opposite sides of the Atlantic, for example, separated by far more water than many of these organisms could ever have crossed.
Also, large-scale geological features on separated continents often match very closely when the continents are brought together: the Appalachian Mountains of North America match the Highlands of Scotland, for example, and the rock strata of the Karoo system of South Africa are identical to the Santa Catarina system of Brazil.
In 1915, Wegener outlined his theory in a book, The Origin Of Continents And Oceans. The theory elegantly explained so many disparate facts that it deserved to be taken very seriously, but it wasn't. The reaction from the scientific community was hostile and harsh. The president of the American Philosophical Society called Wegener's proposal "utter, damned rot". Anyone who "valued his reputation for scientific sanity" would never support such a theory, declared a leading British geologist.
One weakness in Wegener's hypothesis was his failure to propose a credible mechanism to move the continents. He explained their shifts by invoking the centrifugal force of the rotating Earth and the gravitational pull of the sun and moon. Calculations quickly showed these forces could not move continents, however: a ready excuse to dismiss Wegener's ideas. One scientist calculated that a tidal force strong enough to move continents would stop Earth rotating in less than a year.
Despite general rejection, Wegener's ideas attracted some support in the decades that followed. A number of discoveries in paleomagnetism and oceanography convinced most scientists by the late 1960s that continents move. This movement also explains mountains, earthquakes, volcanic eruptions and other phenomena.
We now know that Earth's crust, bearing the continents and the ocean floors, is cracked into giant plates. These float on a layer called the asthenosphere, which is made of rock under such tremendous heat and pressure that it behaves as an extremely viscous liquid.
The plates are moving apart at the great ocean ridges, where molten rock rises from below the crust and hardens into new crust. Where plates collide, great mountain ranges may be pushed up, such as the Himalayas. Wegener's basic insights remain valid, and the categories of evidence he used to support his theory are still being investigated and enlarged.
Leading geologists of the time looked on Wegener as a naive meteorologist meddling in their field. Wegener failed to secure a professorship in Germany despite many applications, and it wasn't until 1924 that he took up a chair in meteorology and geophysics at the University of Graz, in Austria. It would be interesting to compare his scientific legacy with that of the many geologists preferred over him for academic chairs in Germany.
On the ill-fated trip to his beloved Greenland, Wegener heroically headed a small group on a daunting journey in atrocious conditions to bring relief supplies to an outlying station. He died on the way back, probably from a heart attack brought on by extreme exertion.