Timeline of geology - Definition and Overview

Timeline of geology: see also geologic timescale.

• 1620 - Francis Bacon notices the jigsaw fit of the opposite shores of the Atlantic Ocean
• 1669 - Nicolas Steno puts forward his theory that sedimentary strata had been deposited in former seas, and that fossils were organic in origin
• 1701 - Edmund Halley suggests using the salinity and evaporation of the Mediterranean to determine the age of the Earth
• 1743 - Sir Christopher Packe produces a geological map of south-east England
• 1746 - Jean Etienne Guettard presents the first mineralogical map of France to the French Academy of Sciences.
• 1760 - John Michell suggests earthquakes are caused by one layer of rocks rubbing against another
• 1776 - James Keir suggests that some rocks, such as those at the Giant's Causeway, might have been formed by the crystallisation of molten lava
• 1779 - Comte de Buffon speculates that the Earth is older than the 6,000 years suggested by the Bible
• 1785 - James Hutton presents paper entitled Theory of the Earth - earth must be old
• 1799 - William Smith produces the first large scale geological map, of the area around Bath
• 1809 - William Maclure conducts the first geological survey of the eastern United States
• 1830 - Sir Charles Lyell publishes book, Principles of Geology, which describes the world as being several hundred million years old
• 1837 - Louis Agassiz begins his glaciation studies which eventually demonstrate that the Earth has had at least one ice age
• 1862 - Lord Kelvin attempts to find the age of the Earth by examining its cooling time and estimates that the Earth is between 20--400 million years old
• 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--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
• 1913 - Albert Michelson measures tides in the solid body of the Earth
• 1935 - Charles Richter invents a logarithmic scale to measure the intensity of earthquakes
• 1953 - Maurice Ewing and Bruce Heezen discover the Great Global Rift running along the Mid-Atlantic Ridge
• 1960 - Harry Hess proposes that new sea floor might be created at mid-ocean rifts and destroyed at deep sea trenches
• 1963 - F.J. Vine and D.H. 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
• 1980 - Physicist Luis Alvarez, his son, geologist Walter Alvarez, and others propose that the impact of a large extra-terrestrial object caused the extinction of the dinosaurs at the end of the Cretaceous Period, about 65 million years ago.