Brief history of the plate tectonics theory

The theory of plate tectonics, like every scientific theory, resulted from centuries of observations and compilation of many scientists’ works. It started as a hypothesis and had to be proven with hard evidence before being completely accepted by the scientific community.

Photograph of Alfred Wegener taken between 1912 to 1913 (Source: Wikipedia)

Nonetheless, we consider Alfred Wegener, a meteorologist of the beginning of the 20th century, as the father of the theory that he at that time referred to as “the continental drift”. His book The Origin of Continents and Oceans, published in 1915, is widely accepted as the beginning of modern plate tectonics, even if the theory was only widely accepted in a refined version in the 1960s.

The main idea that Wegener and others had was that modern continents formed a single landmass in the past. This idea was supported by simple observations like the fact that South-American and African coastlines fit so well, or that we can find the same fossils in similar sedimentary rocks on both continents.

The theory needed an explanation for continental drift, a process that would account for the motion of tectonic plates. The continental drift was strongly criticised during the first half of the 20th century, until the second world war. During the war, the latest radar technology was used to map the seafloor. Rapidly, evidence pointing to the process of seafloor spreading and effective plate motion was accumulated.

After the war, marine geology was developed, which led to the discovery of the subduction process under the continental margins. Subduction was a perfect way to balance the extension observed at the mid-ocean ridges by recycling oceanic lithosphere in the mantle. Plate tectonics theory then became widely accepted among scientists because it relied on hard evidence and could explain most of the modern geological structures such as ocean basins, mountain ranges, and rifts.