Alfred Wegener, a German meteorologist and geophysicist, introduced his theory of continental drift in the early 20th century. He proposed that continents moved across the Earth’s surface over vast geological time, rather than being static. Despite presenting compelling evidence, Wegener’s ideas faced widespread skepticism and were largely rejected by the scientific community during his lifetime. The scientific establishment found his revolutionary concept difficult to reconcile with the prevailing understanding of Earth’s dynamics.
Wegener’s Radical Idea
Wegener’s theory posited that all continents were once joined in a single supercontinent he named Pangaea. This immense landmass began to break apart approximately 200 million years ago, with fragments slowly drifting to their current positions. To support his hypothesis, Wegener compiled a wide array of observational evidence from various scientific fields.
He noted the striking “jigsaw puzzle” fit of the continents, particularly South America and Africa, when their continental shelves were considered. Identical fossil species of ancient plants and animals were found on widely separated continents, such as Mesosaurus in South America and Africa, and Glossopteris across South America, Africa, India, and Antarctica. These organisms were unlikely to have crossed vast oceans, suggesting the continents were once connected. Wegener also identified matching geological structures, like mountain ranges and rock formations, that aligned across continents when reassembled, such as the Appalachian Mountains in North America correlating with mountain ranges in Greenland, Ireland, and Great Britain. Finally, paleoclimate evidence, including ancient glacial deposits in present-day tropical regions and coal deposits in polar areas, indicated these landmasses had once been in different climatic zones, further supporting their movement.
The Crucial Missing Explanation
The primary reason for the widespread rejection of Wegener’s continental drift theory was his inability to propose a plausible mechanism for how continents could move. The prevailing geological understanding viewed the Earth’s crust as rigid and stationary, making the idea of continents plowing through solid oceanic crust seem impossible. Scientists calculated that the forces Wegener suggested were far too weak to overcome the immense resistance of the Earth’s crust.
Wegener speculated that forces such as the centrifugal force from Earth’s rotation and tidal forces from the sun and moon could be responsible for continental movement. However, geophysicists quickly demonstrated that these forces were infinitesimally small compared to what would be needed to move entire continents. One scientist even calculated that a tidal force strong enough to move continents would cause the Earth to stop rotating in less than a year. Without a convincing explanation of “how” the continents moved, the compelling observational evidence Wegener presented was largely dismissed as coincidence or misinterpretation.
Skepticism and Established Beliefs
Beyond the lack of a credible mechanism, several other factors contributed to the rejection of Wegener’s hypothesis. His professional background as a meteorologist and astronomer, rather than a geologist, led some established geologists to view him as an outsider. This perception fueled resistance within the geological community. The dominant geological theories of the era explained Earth’s features through vertical movements, such as the contraction theory for mountain formation or the concept of land bridges to explain scattered fossil records.
These long-held paradigms made it difficult for scientists to accept a radical shift to horizontal continental movement. Critics also pointed to perceived inaccuracies or oversimplifications in some of Wegener’s data or interpretations. For instance, the assumption that continents fit together along their current coastlines, rather than the true edges of their submerged continental shelves, was one area of criticism. This resistance to revolutionary ideas meant that deeply entrenched beliefs were not easily overturned without overwhelming and undeniable evidence, which Wegener, despite his extensive observations, could not fully provide at the time.