Triassic Period

Continents During the Triassic Period

Who discovered seafloor spreading?

Harry Hess (1906–1969), an American geologist and professor of geology at Princeton University, discovered seafloor spreading. Based on material brought up from the ocean floor during a drilling project, he determined that rocks on the ocean floor were younger than those on the continental landmasses. He also discovered rocks on the ocean floor varied in age: there were older rocks farther from the mid-ocean ridges and younger rocks around mid-ocean ridges. Hess proposed that the seafloor was spreading as magma erupted from Earth’s interior along the ocean’s mid-ocean ridges. The newly created seafloor slowly spreads away from the ridges, and later sinks back into Earth’s interior around deep-sea trenches.


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