History of the Development of Plate Tectonic Theory

Alfred Wegener

May 1, 1912

Alfred Wegener notices that the coasts of South America and Africa could fit together like a puzzle. He proposed the idea of Pangaea where all land masses were together as one super continent.

Mid-Atlantic Ridge Confirmed by Sonar

May 1, 1925

Discovery of the Mid-Atlantic Ridge

Arthur Holmes

Jan 1, 1929

Arthur Holmes elaborated on Wegener's theory that the continents are moved on convection currents in the mantle.

Thin Sediment Layer

Sep 14, 1947

Seismologists on the U.S. research ship Atlantis found that the sediment layer on the floor of the Atlantic was much thinner than originally thought. They didn't knwo why atthe time, but later study would reveal that sea floor spreading could cause such an occurance.

Mapping of the Ocean Floors

Sep 14, 1950

In the 1950s the mapping of the ocean floors was undertaken.

Sea Floor Spreading

Feb 5, 1961

Harry Hess (1962) and R.Deitz (1961) published the sea floor spreading theory after the discovery of the Mid-Atlantic Ridge.