Editing Timeline of geology (section)

==20th century==
* 1903 – [[George Darwin]] and [[John Joly]] claim that radioactivity is partially responsible for the Earth's heat
* 1907 – [[Bertram Boltwood]] proposes that the amount of lead in uranium and thorium ores might be used to determine the Earth's age and 	crudely dates some rocks to have ages between 410 and 2200 million years
* 1911 – [[Arthur Holmes]] uses radioactivity to date rocks, the oldest being 1.6 billion years old
* 1912 – [[Alfred Wegener]] proposes that all the continents once formed a single landmass called Pangaea that broke apart via [[continental drift]]
* 1912 – [[George Barrow (geologist)|George Barrow]] maps zones of [[metamorphism]] (the Barrovian sequence) in southern [[Scotland]]
* 1913 – [[Albert A. Michelson]] measures [[tide]]s in the solid body of the Earth
* 1915 – [[Pentti Eskola]] develops the concept of [[metamorphic facies]]
* 1928 – [[Norman L. Bowen|N. L. Bowen]] publishes ''The Evolution of the Igneous Rocks,'' revolutionizing experimental [[igneous]] [[petrology]]
* 1935 – [[Charles Richter]] invents a logarithmic scale to measure the magnitude of [[earthquake]]s (<math>M_L</math>)
* 1941 – [[Nickel-Strunz classification]], [[Karl Hugo Strunz|Karl H. Strunz]], ''Mineralogische Tabellen''
* 1948–1959 – [[Felix Andries Vening Meinesz]] investigations show gravity anomalies, implying that the crust is moving (together with [[Johannes Herman Frederik Umbgrove|J.H.F. Umbgrove]], [[Berend George Escher|B.G. Escher]] and [[Philip Henry Kuenen|Ph.H. Kuenen]])
* 1951 – [[Alfred Rittmann]] links [[subduction]], [[volcanism]] and the [[Wadati–Benioff zone]]
* 1953 – [[Maurice Ewing]], [[Bruce Heezen]], and [[Marie Tharp]] discover the [[Great Global Rift]] running along the [[Mid-Atlantic Ridge]]
* 1960 – [[Harry Hammond Hess|Harry Hess]] proposes that new sea floor might be created at mid-ocean rifts and destroyed at deep sea trenches
* 1963 – [[Frederick Vine]] and [[Drummond Matthews]] explain the stripes of magnetized rocks with alternating magnetic polarities running parallel to mid-ocean ridges as due to sea floor spreading and the periodic geomagnetic field reversals ([[Vine–Matthews–Morley hypothesis]])
* 1966 – [[Keiiti Aki]] discovers the [[seismic moment]] (<math>M_0</math>)
* 1979 – [[Thomas C. Hanks]] and [[Hiroo Kanamori]], [[Moment magnitude scale]] (<math>M_W</math>), it succeeds the [[Richter magnitude scale]]
* 1980 – Physicist [[Luis Walter Alvarez|Luis Alvarez]], his son, geologist [[Walter Alvarez]], and others propose that the impact of a large extraterrestrial object caused the [[extinction]] of the [[dinosaur]]s at the [[Cretaceous–Paleogene extinction event|end of the Cretaceous Period]], about 66 million years ago.