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 23rd October 4004 BC

The date appeared in the front of Bibles until as late as 1915!

Considered to be the first Geologist

The Law of Superposition

Principle of Original Horizontality

Principle of Lateral Continuity

Nicolaus Steno 1638-1686 Danish

James Hutton 1726-1797 Scottish

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

Hutton’s unconformity at Siccar Point

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

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.

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

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) EnglishStudied 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 ItalianVolcanologist 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 resistant construction

Johannes Walther (1860-1937) German

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

Proposed Walther’s Law of Facies

Milutin Milankovitch (1879-1958) Serbian

Serbian civil engineer and geophysicistProposed 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 GermanProposed the Theory of Continental Drift in1915 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 20th 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 the 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

and 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 1992Suggested 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!