Alfred Wegener, a German meteorologist and geophysicist, first presented his concept of continental drift in 1912. He proposed that the Earth’s continents were once joined in a single supercontinent he named Pangaea. Wegener suggested this massive landmass began to break apart around 200 million years ago, with the resulting fragments slowly moving to their current positions. While this core idea was later validated and incorporated into the modern theory of Plate Tectonics, the original hypothesis was met with strong skepticism and rejection by the geological community for decades.
Wegener’s Supporting Evidence
Wegener compiled a compelling array of evidence from multiple scientific disciplines to support his hypothesis that continents were mobile. He noted the remarkable “jigsaw puzzle” fit of the continental coastlines, particularly the eastern coast of South America and the western coast of Africa, which appeared to match almost perfectly. He also showed that ancient fossils of the same species were found across vast oceans. Examples include the freshwater reptile Mesosaurus found in both South America and Africa, and the Glossopteris seed fern found on four separate southern continents.
The distribution of ancient climate indicators also supported continental movement. For instance, glacial deposits (tillites) from the Permo-Carboniferous period were discovered in tropical regions like India and Africa, suggesting these landmasses had once been located closer to the South Pole. Wegener also found matching geological structures and rock types on continents now separated by the Atlantic Ocean. Mountain ranges in the eastern United States and Canada aligned with ranges in Greenland, the British Isles, and Norway. Despite these observations, the geological community remained unconvinced, primarily due to a significant gap in the theory.
The Missing Engine of Movement
The primary reason for the rejection of continental drift was Wegener’s inability to propose a plausible physical mechanism capable of moving entire continents. Wegener suggested two main forces: a “polflucht,” or polar fleeing force, related to the Earth’s centrifugal force from rotation, and tidal friction caused by the gravitational pull of the Sun and Moon. He theorized that continents, composed of lighter granitic rock, were “plowing” through the denser basaltic rock of the ocean floor.
Physicists and geophysicists quickly calculated that both the centrifugal and tidal forces were far too weak to generate the power required to overcome the friction of the ocean crust. Harold Jeffreys, a prominent English geophysicist, argued that it was mechanically impossible for solid rock to simply plow through the ocean floor without breaking apart. Since the proposed driving forces were scientifically inadequate, the hypothesis was dismissed as physically impossible by the scientific establishment.
Challenging Geological Orthodoxy
Beyond the mechanical flaw, institutional resistance contributed to the theory’s rejection because Wegener’s ideas challenged the prevailing geological orthodoxy. The dominant view was “fixism,” the belief that continents and ocean basins were permanent and static features of the Earth’s surface. Geologists preferred alternative explanations for the matching evidence, such as the theory of sunken land bridges that had once connected continents and later subsided beneath the ocean.
Another widely accepted theory was the contraction theory, which suggested that the Earth was slowly cooling and shrinking. This cooling caused the crust to buckle and wrinkle, forming mountain ranges. Furthermore, Wegener was not a trained geologist but a meteorologist, making it easier for the established geological community to dismiss his interdisciplinary findings as the speculation of an outsider. The American Association of Petroleum Geologists, for example, organized a symposium to formally oppose the theory, reflecting professional skepticism.
New Data Confirming the Concept
The rejection of continental drift persisted until the 1950s and 1960s, when new technological advancements provided the necessary evidence and the correct mechanism. Extensive post-World War II oceanographic surveys revealed the Mid-Ocean Ridge system, a continuous, submerged mountain range running through the world’s oceans. This discovery led to the concept of seafloor spreading, where new oceanic crust is created at these ridges and moves outward.
Further confirmation came from paleomagnetic studies of the ocean floor, which revealed symmetrical patterns of magnetic stripes on either side of the mid-ocean ridges. These stripes recorded the periodic reversals of the Earth’s magnetic field, proving that the ocean floor was moving and carrying the continents. This new framework, known as Plate Tectonics, identified the correct driving force: convection currents within the Earth’s mantle. These currents slowly circulate heat and drag the tectonic plates across the surface.