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Lecture 2: Landmarks in the Discovery of Geologic Time
January 18, 2018
*********************************** Useful links to Geological Time: Berkeley Time Machine http://www.ucmp.berkeley.edu/help/timeform.html US Geological Survey Time http://pubs.usgs.gov/gip/geotime/contents.html ********************************
Great Discoverers of Time
Aristotle (384-322 BC): summarized Greek knowledge to date; fossils were once living creatures; land and sea changed places in cyclical fashion; surmised long span of time. Leonardo da Vinci (1452-1519): recorded in his notebooks that fossils were once-living creatures; inferred a long expanse of time; argued against the biblical deluge as the cause of fossils found high in mountain ridges. Nicolaus Copernicus (1473-1543): revived the principle of heliocentric planetary motion, an idea originating in classical Greece (see Pythagoras, Philolaus, Aristarchus) but suppressed as blasphemous for 1600 years (De Revolutionibus; also see White, 1896). James Usher, Bishop of Armagh (1581-1656): continued a long tradition by Scriptural scholars in establishing a chronology of Biblical events, and calculated the Creation of Earth to have been in 4004 B.C., an estimate published in 1650 in his "Annals of the Ancient and New Testament" (see White, 1896) Nicolaus Steno (1638-1686): "Dissection of a Shark's Head" (1667) established that fossil shark teeth were in fact the teeth of sharks that became buried as the sediments enclosing them were deposited by water (his first treatise on geology); "De solido intra solidum naturaliter contento dissertationis prodromus" [Concerning a solid body enclosed by process of Nature within a solid] (1669), (his second treatise on geology); principle of original horizontality of sedimentary rocks, and the principle of superposition. Isaac Newton (1642-1727): modern theory of planetary motion; theory of gravitation. James Hutton (1726-1797): Theory of the Earth (1788, published as a paper); Theory of the Earth with Proofs & Illustrations (1795, a two-volume book); proposed the "rock cycle." Georges Cuvier (1769-1832): founded comparative anatomy and paleontology; demonstrated the fact of organic extinction (1796). lithograph of Cuvier. William Smith (1769-1839); used fossils for correlation and demonstrated principle of faunal succession; developed first stratigraphic classification based on time relations of strata; produced first geological map (1815).` Charles Lyell (1797-1875): Principles of Geology (three volumes, published 1830-1833); established the doctrine of uniformitarianism. Charles Darwin (1809-1882): theory of evolution; voyage of the Beagle 1831-1836; published Origin of Species (1859). Henri Becquerel (1852-1908): discovered natural radioactivity (1896). Pierre (1859-1906) and Marie (1867-1934) Curie: discovered that radium continuously releases newly generated heat. Arthur Holmes: first used radioactivity as a means of dating rocks (1911).
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