<< back

Plate Tectonics Lesson

next >>

Continental Drift

Alfred Wegener (1880-1930) was a German polar researcher, geophysicist and meteorologist. He was first interested in polar meteorology, but became interested in geophysics when he noted how well the continents fit together in 1910. He continued to study the continents while teaching at University of Marburg and while serving in WWI (where he was wounded twice). He published his ideas on continental drift 1915 in a publications entitled Die Entstehung der Kontinente und Ozeane (“The Origin of Continents and Oceans”), but his ideas were a radical departure from the accepted beliefs of the time.

His primary evidence for this hypothesis are as follows:

Fit of the continents - like everyone else, he noted how nicely one side of the Atlantic Ocean fits with the other. Wegener called this supercontinent "Pangaea".

Rock type & structural similarities - Wegener also noted that the rocks on both sides of the Atlantic Ocean were metamorphic rocks, a type of rock that forms during mountain building events (like the Himalayas). Rocks are changed to a new rock type due to heat and pressures unlike that in which they first formed. They also followed a pattern: rocks at the center were subjected to the highest heat and pressure, and had a specific set a rock types and minerals as a result, and rocks further away showed less heat and pressure and different rock and mineral assemblages. Wegener believed that Pangaea came together as one large continent and formed a huge mountain range - as tall as or taller than the Himalayas today - and then broke apart sometime later along the same area where it had once come together.

Fossil evidence - Like Suess and others before him, Wegener noted the similarities between fossils now located on continents far apart. But it was more than this. He also noted that the fossils were of organisms from environments considerably different from what they are like today.

Paleoclimatic evidence - This realization that the fossils not only match across continents but also are in different climatic areas indicated that the paleoclimates (past climates) could be mapped across Pangaea as well.

Glacial Evidence - Scientists had long puzzled over how evidence of glaciers could be found in areas like South Africa and Australia which are today very hot. When the continents are put together, one can see how the Antarctic Ice Sheet extends north into South America, South Africa, India and Australia. As Pangaea broke up, the ice sheets melted, leaving behind the evidence that they were once there.

Ideas that are a radical departure from the norm are not usually well accepted. Wegener's ideas were largely ridiculed by the scientific community at large. The largest hurdle he had to overcome was getting people to accept that the continents moved. He, himself, had problems with this. He speculated the following mechanisms:

His ideas were so controversial that he had a hard time getting a professorship at universities. This did not stop him from continuing this and other research.

In 1930 he headed to Greenland for his forth expedition. Wegener died on this expedition at the age of 50.

"Wegener probably would have been part of the plate-tectonics revolution, if not the actual instigator, had he lived longer.“ (Dr. Peter R. Vogt)

Photograph of the German expedition and overwintering in Greenland - Alfred Wegener (left) and Rasmus Villumsen (inuit) at station Eismitte. Last photo, both died presumably around the 16th November on the way back to the coast. Vehicles used by the 1930 expedition

<< back


next >>

copyright Sonjia Leyva 2015