Continental drift
Theory of moving continents, rejected then validated.
Continental drift describes how Earth’s continents shift positions relative to one another across geologic time. When first proposed as a scientific theory in the early 1900s, the notion that continents could move was largely dismissed. Since then, however, the idea has been thoroughly confirmed and is now a core part of plate tectonics, the science that explains how continents travel atop slabs of the Earth’s lithosphere.
The earliest known speculation that continents might have drifted came from Abraham Ortelius in 1596. Austrian geologist Otto Ampferer was an early proponent of the modern mobilist view. The concept was independently and more fully developed by Alfred Wegener in 1912, and he expanded it into a book, *Die Entstehung der Kontinente und Ozeane* (The Origin of Continents and Oceans), published in 1915. At the time, many rejected his hypothesis, mainly because no known geological mechanism could drive such massive movements. In 1931, English geologist Arthur Holmes proposed mantle convection as that mechanism, now understood to be powered by radioactive decay, primordial heat, and a much smaller contribution from tidal heating.
**History**
**Early history**
Abraham Ortelius (1596), Theodor Christoph Lilienthal (1756), Alexander von Humboldt (1801 and 1845), Antonio Snider-Pellegrini (1858), and others had earlier noticed that the shapes of continents on opposite sides of the Atlantic Ocean—especially Africa and South America—appear to fit together. W. J. Kious described Ortelius’s thinking: in his work *Thesaurus Geographicus*, Ortelius suggested that the Americas were “torn away from Europe and Africa … by earthquakes and floods,” adding that “the vestiges of the rupture reveal themselves if someone brings forward a map of the world and considers carefully the coasts of the three [continents].”
In 1889, Alfred Russel Wallace noted that it was once widely believed, even among geologists, that Earth’s major surface features, both large and small, were constantly changing, and that over geologic time continents and oceans had repeatedly swapped places. He quoted Charles Lyell as saying, “Continents, therefore, although permanent for whole geological epochs, shift their positions entirely in the course of ages,” and claimed that James Dwight Dana, in 1849, was the first to cast doubt on this idea.
In his *Manual of Geology* (1863), Dana wrot
- first_suggested_by
- Abraham Ortelius (1596)
- pioneer_of_modern_view
- Otto Ampferer
- independently_developed_by
- Alfred Wegener (1912, 1915)
- driving_mechanism_proposed_by
- Arthur Holmes (1931)
- field
- Geology / Geophysics
- known_for
- Movement of continents over geologic time, now part of plate tectonics
Lore & Background
The speculation that continents might have drifted was first put forward by Abraham Ortelius in 1596. A pioneer of the modern view of mobilism was Austrian geologist Otto Ampferer. The concept was independently and more fully developed by Alfred Wegener in 1912, and expanded into book form with his 1915 publication, Die Entstehung der Kontinente und Ozeane (The Origin of Continents and Oceans). However, at that time his hypothesis was rejected by many, largely because there was no known geological mechanism which could propel such massive movements. In 1931, English geologist Arthur Holmes proposed mantle convection for that mechanism, which is now known to be powered by radioactive decay and primordial heat and a much smaller amount of heat from tidal heating.
Earlier observers, including Abraham Ortelius, Theodor Christoph Lilienthal, Alexander von Humboldt, and Antonio Snider-Pellegrini, had noted that the shapes of continents on opposite sides of the Atlantic Ocean seem to fit together. Ortelius suggested the Americas were 'torn away from Europe and Africa ... by earthquakes and floods.' Eduard Suess proposed a supercontinent Gondwana in 1885, and the Tethys Ocean in 1893. French geographer Elisée Reclus presented evidence for a supercontinent and theorized continental drift fifty years prior to Wegener in his 1872 work The Earth.
Alfred Wegener first presented his hypothesis to the German Geological Society on 6 January 1912. He proposed that the continents had once formed a single landmass, which he called Pangaea, before breaking apart and drifting to their present locations. Wegener was the first to use the phrase 'continental drift' (1912, 1915) and to publish the hypothesis that the continents had somehow drifted apart. Although he presented much evidence, he was unable to provide a convincing explanation for the physical processes. He suggested that the continents had been pulled apart by the centrifugal pseudoforce of the Earth's rotation or by astronomical precession, but calculations showed the force was not sufficient.
Reader's Guide
Continental drift is significant because it transformed the understanding of Earth's history and geology, eventually becoming a cornerstone of plate tectonics. The theory was initially rejected for decades due to the lack of a plausible driving force and because Wegener's estimate of the speed of continental motion (250 cm/year) was implausibly high; the currently accepted rate for the separation of the Americas from Europe and Africa is about 2.5 cm/year. Arthur Holmes's 1931 proposal of mantle convection provided a mechanism, but the theory only gained widespread acceptance later. The rejection of the theory was also influenced by the 'Permanence theory' championed by James Dwight Dana, which held that continents and oceans had fixed outlines since earliest time. The exploration of the deep sea beds by the Challenger expedition (1872–1876) appeared to confirm this by showing that land debris is deposited close to shore on the continental shelf, suggesting oceans were permanent. Despite opposition from fixists like Hans Stille and Leopold Kober, continental drift has been extensively validated and is now incorporated into plate tectonics. The legacy of the theory includes the recognition that the details of the forces propelling the plates are still poorly understood even today.
Did You Know?
- Abraham Ortelius first suggested continental drift in 1596, proposing the Americas were 'torn away from Europe and Africa by earthquakes and floods.'
- Alfred Wegener first presented his hypothesis on 6 January 1912 and coined the phrase 'continental drift' in 1912 and 1915.
- Arthur Holmes proposed mantle convection as the driving mechanism for continental drift in 1931, powered by radioactive decay and primordial heat.
- Wegener's estimate of continental motion (250 cm/year) was implausibly high; the currently accepted rate for the separation of the Americas from Europe and Africa is about 2.5 cm/year.
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