Notable contributors to the development of Geology

Georgius Agricola (1494 -1555) German Regarded as the Father of Mineralogy Completed De Re Metallica in 1550, a systematic treatise on mining and extractive metallurgy De Re Metallica remained unsurpassed for two centuries following its publication in 1556

Archbishop James Ussher 1581 -1656 Irish First person to attempt a calculation of the age of the Earth Based on studying the Bible and other Middle Eastern religious texts Calculated how long it would have taken for all the stories in the texts to have been played out in real time In 1650 calculated the age of the creation to have been nightfall preceding Sunday 23 rd October 4004 BC The date appeared in the front of Bibles until as late as 1915!

Nicolaus Steno 1638 -1686 Danish Considered to be the first Geologist The Law of Superposition Principle of Original Horizontality Principle of Lateral Continuity

James Hutton 1726 -1797 Scottish Hutton’s unconformity at Siccar Point Proposed the concept of Uniformitarianism Discovered that Granite solidified from a molten state Discovered angular unconformities and recognised their significance Proposed the concept of Deep Time and Gradualism

Georges Cuvier (1769 -1832) French Proposed the concept of extinction following the study of Mastodon and Giant Sloth bones Proposed the concept of Catastrophism, whereby features of the Earth could be explained by short-lived and infrequent catastrophic events

William Smith 1769 -1839 English Published the first ever Geological map in 1799 (Bath area) Published the first Geological Map of Britain in 1815 Proposed the Principle of Faunal Succession Considered to be the ‘Father of English Geology’

Friedrich Mohs 1773 -1839 German Devised Mohs’ Scale of Hardness for Minerals in 1812 Based on the amount of noise generated and the amount of powder produced when minerals are rubbed against a steel file

William Buckland (1784 -1856) English Wrote the first full account of a fossil dinosaur which he named Megalosaurus Pioneer in the use of fossilized faeces, for which he coined the term coprolites, to reconstruct ancient ecosystems Studied bones in Kirkdale Cave Yorkshire and concluded they were not due to the effects of the Great Flood Buckland kept various animals inside his house, some dangerous. He was determined to eat every animal ever discovered, and was able to find qualities he liked in all except the common mole, which he deemed disgusting. A table made entirely of his coprolite specimens was also in his possessions. Did his fieldwork wearing an academic gown.

Adam Sedgwick (1785 -1873) English Regarded as one of the founders of modern geology Proposed the Devonian period and later the Cambrian period of the geological time scale Guided Darwin in his early studies of Geology but was later an outspoken opponent of his Theory of Evolution

Roderick Murchison (1792 -1871) English Proposed the Silurian System in 1839, the first stratigraphic division based on the fossil content rather than rock types Later helped clarify the Devonian System, and after a visit to Russia, The Permian

Charles Lyell (1797 -1875) Scottish Published Principles of Geology in 1830 in 3 volumes. A groundbreaking and influential textbook on Geology. Believed in the principle of Uniformitarianism and challenged the accounts of creation in Genesis in the Bible Principles of Geology had a profound influence on Darwin and was pivotal in his ideas on evolution and natural selection

Mary Anning 1799 -1847 English Collected and sold fossils in Lyme Regis, Dorset Discovered the first complete Ichthyosaur, Plesiosaur and Pterosaur skeletons The song ‘she sell seashells on the seashore’ is thought to have been written about Mary Anning

Louis Agassiz (1807– 1873) Swiss American Referred to as the Father of Glaciology Studied glaciers in the Swiss Alps and landscape in Scotland Proposed that an Ice Age affected most of the Northern hemisphere from 10, 000 to 2 million years ago

Charles Darwin (1809 -1882) English Studied Geology at Cambridge and was a member of the scientific crew on ‘The Voyage of the Beagle’ Proposed the Theory of Evolution through the process of natural selection and the concept of ‘survival of the fittest’ Published The Origin of Species in 1859

Eduard Suess (1831 -1914) Austrian Proposed the Theory of Eustasy and the concept of marine transgressions and regressions Proposed the existence of a former ocean between Africa and Europe which he named the Tethys Ocean Proposed the existence of Gondwanaland from studying the glossopteris fern in India, South America and Africa

Giuseppe Mercalli 1850 -1914 Italian Volcanologist who developed the Mercalli Scale to measure the intensity of earthquakes in 1902 Based on eye-witness observations of damage at different distances from the epicentre Originally a ten point scale in roman numerals, later expanded to 12 points by Charles Richter and known as the Modified Mercalli Scale

Charles Doolittle Walcott (1850 -1927) American Discovered the Burgess Shale in Canada in 1909, a Cambrian lagerstatten Between 1910 and 1924 Walcott and his two sons collected over 65, 000 specimens from what is now known as the Walcott Quarry

Andrija Mohorovičić (1857 -1936 Croatian) From the study of seismic waves he discovered the boundary between the crust and the mantle This boundary is known as the Mohorovicic Discontinuity or Moho Devised a technique for locating the epicentres of earthquakes Early advocate of earthquake resistan construction

Johannes Walther (1860 -1937) German Proposed Walther’s Law of Facies The concept that a vertical succession of facies reflects lateral changes in environment If depositional environments "migrate" laterally, then sediments of one environment come to lie on top of another Explained by the idea of marine transgressions/regressions

Milutin Milankovitch (1879 -1958) Serbian civil engineer and geophysicist Proposed a mechanism to explain the causes of glaciation and de-glaciation Changes in Earth’s orbit responsible for climate change Precession, Obliquity and Eccentricity fluctuations known as Milankovitch Cycles

Alfred Wegener 1880 -1930 German Proposed the Theory of Continental Drift in 1915 but was unable to explain the mechanisms that caused the movements of the continents Produced the first supercontinent reconstruction and named it Pangea

Norman L. Bowen (1887 -1956) Canadian Recognised as the Greatest Petrologist of the 20 th Century Discovered the relationship between temperature, pressure and the melting points of silicate minerals in what he named ‘Bowen’s Reaction Series’. Developed Phase Diagrams to explain how minerals crystallised from melts.

Inge Lehmann (1888 -1993) Danish Proposed in 1936 that the Earth’s core is not a single molten sphere but has a solid inner component. Deduction based on the study of refracted P waves.

Arthur Holmes 1890 -1965 English Considered to be the ‘Father of the Geological Timescale’ Pioneered absolute dating using radioactive isotopes Dated the Earth as 1. 6 billion years old in 1913 Revised the date of the Earth to 4, 500 million years +/- 100 million years in 1950 Published the groundbreaking ‘Principles of Geology’ in 1944

Charles Richter 1900 -1985 American Developed the Richter Scale in 1935 with colleague Beno Gutenberg for measuring the magnitude of earthquakes Became involved in earthquake engineering and developed building codes for earthquake prone areas such as Los Angeles Published ‘Seismicity of the Earth’ in 1941 and the second edition in 1954 is considered a standard reference in the field of Seismology

Harry Hammond Hess (1906 -1969) American A founding father of Plate Tectonic Theory Developed theory of Sea Floor Spreading Demonstrated the relationship between Volcanic Island Arcs and Gravity Anomalies Involved with the Mohole Project or Deep Sea Drilling Project

John Tuzo Wilson (1908 -1993) Canadian Developed the Wilson Cycle a model to explain how continents rift apart and how oceans open and close Proposed the Hot Spot theory to explain the formation of the Hawaiian Islands

Mary Leakey (1913 -1996) English Discovered the first skull of a fossil ape on Rusinga Island an Australopithecine called Zinianthropus at Olduvai With husband Louis uncovered the tools and fossils of ancient hominines at Olduvai and she discovered the Laetoli footprints 3. 6 Ma

Walter Alvarez (1940 -Present) American Developed the Asteroid Impact theory that resulted in the major mass extinction at the Cretaceous. Tertiary (K-T) Boundary 65 Ma

Joseph L. Kirschvink (1953 -Present) American Paul F. Hoffman (1941 -Present) Canadian Developed the Snowball Earth Theory in 1992 Suggested that during the Precambrian between 750 and 650 million years ago the entire surface of planet Earth was encased in ice

That’s All Folks!