Alexander du Toit

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Alexander Logie du Toit
Born 14 March 1878
Died 25 February 1948(1948-02-25) (aged 69)
Residence South Africa, United Kingdom
Nationality South African
Alma mater University of the Cape of Good Hope
Royal Technical College
Drury College
Royal College of Science
Awards Murchison Medal (1933)
Scientific career
Fields Geologist
Institutions Geological Commission of the Cape of Good Hope
De Beers Consolidated Mines

Alexander Logie du Toit FRS [1] ( /dˈtɔɪ/ doo-TOY; 14 March 1878 – 25 February 1948) was a geologist from South Africa, and an early supporter of Alfred Wegener's theory of continental drift. [2]

Fellow of the Royal Society Elected Fellow of the Royal Society, including Honorary, Foreign and Royal Fellows

Fellowship of the Royal Society is an award granted to individuals that the Royal Society of London judges to have made a 'substantial contribution to the improvement of natural knowledge, including mathematics, engineering science and medical science'.

Alfred Wegener German meteorologist, geologist and astronomer

Alfred Lothar Wegener was a German polar researcher, geophysicist and meteorologist.

Continental drift The movement of the Earths continents relative to each other

Continental drift is the theory that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596. The concept was independently and more fully developed by Alfred Wegener in 1912, but his theory was rejected by many for lack of any motive mechanism. Arthur Holmes later proposed mantle convection for that mechanism. The idea of continental drift has since been subsumed by the theory of plate tectonics, which explains that the continents move by riding on plates of the Earth's lithosphere.

Contents

Early life and education

Du Toit was born in Newlands, Cape Town in 1878 and educated at the Diocesan College in Rondebosch and the University of the Cape of Good Hope. Encouraged by his grandfather, Captain Alexander Logie, he graduated in 1899 in mining engineering at the Royal Technical College in Glasgow. After a short period studying geology at the Royal College of Science in London, he returned to Glasgow to lecture in geology, mining and surveying at the University of Glasgow and the Royal Technical College.

Newlands, Cape Town Place in Western Cape, South Africa

Newlands is an upmarket suburb of Cape Town, South Africa. It is located at the foot of Table Mountain in the Southern Suburbs of Cape Town, and is the wettest suburb in South Africa due to its high winter rainfall. It is home to a number of schools, including the oldest school in the country, South African College Schools (SACS) Junior and High Schools, as well as the Newlands Forest.

Diocesan College South African secondary school

The Diocesan College, or Bishops as it is more commonly known, is an independent day and boarding all-boys school situated in the suburb of Rondebosch in Cape Town, South Africa. The school was established in 1849 by Robert Gray, Bishop of Cape Town.

Rondebosch Place in Western Cape, South Africa

Rondebosch is one of the Southern Suburbs of Cape Town, South Africa. It is primarily a residential suburb, with shopping and business districts as well as the main campus of the University of Cape Town.

Career

In 1903, du Toit was appointed as a geologist within the Geological Commission of the Cape of Good Hope, and he began to develop an extensive knowledge of the geology of southern Africa by mapping large portions of the Karoo and its dolerite intrusions, publishing numerous papers on the subject. Subsequently, he mapped the entire Karoo System through the complete stratigraphy from Dwyka tillite to the basalt of the Drakensberg. He worked at a furious rate but was known for his painstaking meticulousness. This is reflected in his book "Our Wandering Continents". [3] It still bears reading for its creative and closely argued theses in the light of the geology of the day, and is soberingly consistent with modern principles of plate tectonics.

The Geological Commission of the Cape of Good Hope was a South African geological survey that published a series of maps and literature of the geology and hydrogeology of South Africa, particularly the Western Cape and surrounding areas during its existence from 1896 to 1911.

Karoo Natural region in South Africa

The Karoo is a semi desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its extent is also not precisely defined. The Karoo is partly defined by its topography, geology and climate, and above all, its low rainfall, arid air, cloudless skies, and extremes of heat and cold. The Karoo also hosted a well-preserved ecosystem hundreds of million years ago which is now represented by many fossils.

Basalt A magnesium- and iron-rich extrusive igneous rock

Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. More than 90% of all volcanic rock on Earth is basalt. Basalt lava has a low viscosity, due to its low silica content, resulting in rapid lava flows that can spread over great areas before cooling and solidification. Flood basalt describes the formation in a series of lava basalt flows.

In 1920 du Toit joined the Union Irrigation Department as water geologist, and in 1927 became chief consulting geologist to De Beers Consolidated Mines, a position he held to his retirement in 1941.

In 1923, he received a grant from the Carnegie Institution of Washington, and used this to travel to eastern South America to study the geology of Argentina, Paraguay and Brazil. As is apparent from his remarks in "Our Wandering Continents", he had not requested support for the expedition on a whim, but specifically to test his predictions of correspondences between the geology of the two continents. In the event he was able to demonstrate and follow the predicted continuation of specific features already documented in Southern Africa, into the continent of South America. Although that might perhaps seem less impressive to the layman, to the geologist this evidence was far more convincing than any arguable ex post facto (Latin for "after the facts") matching of continental shelves.

Argentina federal republic in South America

Argentina, officially named the Argentine Republic, is a country located mostly in the southern half of South America. Sharing the bulk of the Southern Cone with Chile to the west, the country is also bordered by Bolivia and Paraguay to the north, Brazil to the northeast, Uruguay and the South Atlantic Ocean to the east, and the Drake Passage to the south. With a mainland area of 2,780,400 km2 (1,073,500 sq mi), Argentina is the eighth-largest country in the world, the fourth largest in the Americas, and the largest Spanish-speaking nation. The sovereign state is subdivided into twenty-three provinces and one autonomous city, Buenos Aires, which is the federal capital of the nation as decided by Congress. The provinces and the capital have their own constitutions, but exist under a federal system. Argentina claims sovereignty over part of Antarctica, the Falkland Islands, and South Georgia and the South Sandwich Islands.

Paraguay republic in South America

Paraguay, officially the Republic of Paraguay, it is a country of South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Although it is one of the only two landlocked countries in South America, the country has coasts, beaches and ports on the Paraguay and Paraná rivers that give exit to the Atlantic Ocean through the Paraná-Paraguay Waterway. Due to its central location in South America, it is sometimes referred to as Corazón de Sudamérica.

Brazil Federal republic in South America

Brazil, officially the Federative Republic of Brazil, is the largest country in both South America and Latin America. At 8.5 million square kilometers and with over 208 million people, Brazil is the world's fifth-largest country by area and the fifth most populous. Brazil borders every South American country except Chile and Ecuador. Its capital is Brasília, and its most populated city is São Paulo. The federation is composed of the union of the 26 states, the Federal District, and the 5,570 municipalities. It is the largest country to have Portuguese as an official language and the only one in the Americas; it is also one of the most multicultural and ethnically diverse nations, due to over a century of mass immigration from around the world.

In the light of his research du Toit published a review of the stratigraphic and radioisotope evidence from these regions that supported Alfred Wegener's ideas, A Geological Comparison of South America with South Africa (1927). His best-known publication, Our Wandering Continents (1937), expanded and improved this work, and, departing somewhat from Wegener, proposed two original supercontinents separated by the Tethys Ocean, a northern/equatorial Laurasia and a southern/polar Gondwanaland.

Stratigraphy The study of rock layers and their formation

Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has two related subfields: lithostratigraphy and biostratigraphy.

A radionuclide is an atom that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferred to one of its electrons to release it as a conversion electron; or used to create and emit a new particle from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay. These emissions are considered ionizing radiation because they are powerful enough to liberate an electron from another atom. The radioactive decay can produce a stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. However, for a collection of atoms of a single element the decay rate, and thus the half-life (t1/2) for that collection can be calculated from their measured decay constants. The range of the half-lives of radioactive atoms have no known limits and span a time range of over 55 orders of magnitude.

Supercontinent Landmass comprising more than one continental core, or craton

In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, many earth scientists use a different definition: "a clustering of nearly all continents", which leaves room for interpretation and is easier to apply to Precambrian times.

Awards and honours

In 1933, du Toit was awarded the Murchison Medal by the Geological Society of London, and in 1943 became a Fellow of the Royal Society.

In 1949, the year after his death, the Geological Society of South Africa inaugurated a biennial lecture series in his honour that continues to the present day. [4]

In 1973, a 75 km crater on Mars (71.8°S, 49.7°W) was named "Du Toit" in recognition of his work. [5] [6]

Significant publications

Related Research Articles

Plate tectonics The scientific theory that describes the large-scale motions of Earths lithosphere

Plate tectonics is a scientific theory describing the large-scale motion of seven large plates and the movements of a larger number of smaller plates of the Earth's lithosphere, since tectonic processes began on Earth between 3 and 3.5 billion years ago. The model builds on the concept of continental drift, an idea developed during the first decades of the 20th century. The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s and early 1960s.

Laurasia Northern supercontinent that formed part of the Pangaea supercontinent

Laurasia was the more northern of two supercontinents that formed part of the Pangaea supercontinent around 335 to 175 million years ago (Mya). It separated from Gondwana 215 to 175 Mya during the breakup of Pangaea, drifting farther north after the split.

John Tuzo Wilson Canadian geologist

John Tuzo Wilson, CC, OBE, FRS, FRSC, FRSE was a Canadian geophysicist and geologist who achieved worldwide acclaim for his contributions to the theory of plate tectonics.

Du Toit Mountains

The Du Toit Mountains are a group of mountains about 35 miles (56 km) long and 10 miles (16 km) wide, to the south-west of the Wilson Mountains in southeastern Palmer Land, Antarctica. The mountains have peaks rising to 1,700 metres (5,600 ft) and are bounded by Beaumont Glacier, Maury Glacier and Defant Glacier.

Émile Argand was a Swiss geologist.

Karoo Supergroup Widespread Mesozoic stratigraphic unit in southern Africa

The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a period of about 120 million years.

Gustaaf Adolf Frederik Molengraaff Dutch scientist

Gustaaf Adolf Frederik Molengraaff was a Dutch geologist, biologist and explorer. He became an authority on the geology of South Africa and the Dutch East Indies.

Frank Bursley Taylor was an American geologist, the son of a lawyer in Fort Wayne, Indiana. He was a Harvard dropout who studied privately financed in large part by his wealthy father. He became a specialist in the glacial geology of the Great Lakes, and proposed to the Geological Society of America on December 29, 1908 that the continents moved on the Earth's surface, that a shallow region in the Atlantic marks where Africa and South America were once joined, and that the collisions of continents could uplift mountains. His ideas were based on his studies on mountain ranges as the Andes, Rockies, Alps and Himalayas, concluding that these mountains could have been formed only as a result of titanic lateral pressures that thrust the earth's surface upward. His theory was either ignored or opposed by other scientists of his time. He wrote a total ten papers on the subject of continental drift Taylor's ideas about continental drift were independently discovered by Alfred Wegener in Germany three years later, in January 1912, and the theory of continental drift is historically often referred to as the "Taylor-Wegener hypothesis," although Taylor himself disapproved of the hyphenated name. But even with Wegener's extensive extra research the idea did not achieve acceptance until the 1960s when a vast weight of evidence had accrued via Harry Hess, Fred Vine and Drummond Matthews.

Roberto Mantovani geologist

Roberto Mantovani, was an Italian geologist and violinist.

Geological history of Earth The sequence of major geological events in Earths past

The geological history of Earth follows the major events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.

Pangaea Supercontinent from the late Paleozoic to early Mesozoic eras

Pangaea or Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and it began to break apart about 175 million years ago. In contrast to the present Earth and its distribution of continental mass, much of Pangaea was in the southern hemisphere and surrounded by a superocean, Panthalassa. Pangaea was the most recent supercontinent to have existed and the first to be reconstructed by geologists.

The evolution of tectonophysics is closely linked to the history of the continental drift and plate tectonics hypotheses. The continental drift/ Airy-Heiskanen isostasy hypothesis had many flaws and scarce data. The fixist/ Pratt-Hayford isostasy, the contracting Earth and the expanding Earth concepts had many flaws as well.

The Du Toit Nunataks are a group of nunataks between Cornwall Glacier and Glen Glacier, marking the western end of the Read Mountains, Shackleton Range. They were photographed from the air by the U.S. Navy, 1967, and surveyed by the British Antarctic Survey, 1968–71. In association with the names of geologists grouped in this area, they were named by the UK Antarctic Place-Names Committee after Alexander Logie du Toit, a South African geologist.

The Dwyka River is located in the Karoo region, in South Africa. It flows from the North-west, joining the Gamka River as a tributary at the Gamka Dam.

The geology of South Africa is highly varied including cratons, greenstone belts, large impact craters as well as orogenic belts. The geology of the country is the base for a large mining sector that extracts gold, diamonds, iron and coal from world-class deposits. The geomorphology of South Africa consists of a high plateau rimmed to west, south and southeast by the Great Escarpment and rugged mountains beyond this there is strip of narrow coastal plain.

Corystospermaceae

Corystospermaceae is a natural family of seed ferns (Pteridospermatophyta) also called Umkomasiaceae, and first based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa The leaves of Dicroidium were recognized by Alex Du Toit to unite all the countries of the Gondwana supercontinent during the Triassic: Africa, South America, India, and Australia. Subsequently, Dicroidium was found in the Triassic of Antarctica and New Zealand, and also the Permian of Jordan. According to the form generic system of paleobotany, leaves are given separate generic names to ovulate and pollen organs, but the discovery of these reproductive organs in Africa by Thomas, and subsequently throughout Gondwana, strengthened Du Toit's concept of a continuous southern supercontinent.

Boris Choubert French geologist

Boris Choubert or Schuberth was a French geologist. An adept of Wegener's theory, he was the first to precisely reconstruct the layout of the continental masses of Africa, America, Europe and Greenland prior to the fragmentation of Pangaea, thirty years before the article generally credited for this discovery.

References

  1. Haughton, S. H. (1949). "Alexander Logie du Toit. 1878-1948". Obituary Notices of Fellows of the Royal Society . 6 (18): 385. doi:10.1098/rsbm.1949.0004. JSTOR   768931.
  2. Hancock, Paul L.; Skinner, Brian J.; Dineley, David L. (2000), The Oxford Companion to The Earth, Oxford University Press, ISBN   0-19-854039-6
  3. du Toit, A.L. (1937) Our Wandering Continents; An Hypothesis of Continental Drifting, Oliver & Boyd, London, UK
  4. The De Beers Alex du Toit Memorial Lecture 2006, Geological Society of South Africa, retrieved 9 July 2007
  5. Du Toit crater Archived 7 July 2006 at the Wayback Machine ., Atlas of Mars Archived 22 February 2006 at the Wayback Machine ., NASA, retrieved 9 July 2007
  6. Du Toit crater, Google Mars, retrieved 10 July 2007