Not a fact anymore
What we know now
Earth’s rigid outer layer is divided into tectonic plates that move relative to one another. Continents form parts of these plates and are carried along as the plates move.
Why it changed
Ocean-floor mapping, seafloor spreading, symmetrical magnetic patterns in oceanic crust, the ages of seafloor rocks, and the global distribution of earthquakes and volcanoes produced a unified explanation for continental movement during the 1950s and 1960s.
- Status
- Superseded
- Accepted approximately
- 19th century to the mid-20th century
- Changed approximately
- 1950s–1960s
Continental drift and plate tectonics are related, but they are not identical theories. Alfred Wegener proposed that continents moved, but his original model did not correctly explain how that movement occurred. Modern plate tectonics holds that continents are embedded within larger lithospheric plates rather than independently ploughing through stationary oceanic crust.
Plate tectonics is firmly established, and plate motion can now be measured directly. Scientists nevertheless continue to study details such as when plate tectonics began on the early Earth and the relative importance of mantle convection, slab pull, ridge push, and other forces in driving individual plates.
The historical dates are approximate. Wegener presented continental drift in 1912, the fixed-Earth framework remained dominant through much of the first half of the 20th century, and modern plate tectonics became broadly accepted during the 1960s.