Plate Tectonics Evidence

The story of plate tectonics is one of science's greatest paradigm shifts — from ridicule to consensus within 40 years. Alfred Wegener proposed continental drift in 1912, noticing that the coasts of Africa and South America fit together like puzzle pieces and that identical fossils and rock formations appeared on both continents. He was widely mocked by the geological establishment because he couldn't explain the mechanism (how could continents plow through ocean crust?). The key breakthrough was seafloor spreading, discovered in the 1950s-60s: mid-ocean ridges (where new ocean crust is created) produce symmetrical magnetic reversals preserved in the seafloor rock — a tape recorder of Earth's magnetic history. Harry Hess proposed seafloor spreading in 1960; the Vine-Matthews-Morley hypothesis (1963) explained the magnetic anomalies; and by the late 1960s, plate tectonics was accepted by essentially all geologists. The theory explains earthquakes (plate boundaries), volcanoes (subduction zones, hotspots), mountain building (colliding plates), and the distribution of life (explaining why fossils of identical species appear on separate continents).