(Alfred Wegener's "Entstehung der Kontinente" dispensed wi...)
Alfred Wegener's "Entstehung der Kontinente" dispensed with land bridges and parallel evolutions and offers an economical concept. Wegener proposed that in the remote past the earth's continents were not separate (as now), but formed one supercontinent which later split apart, the fragments gradually drifting away from one another.
(In this book, the authors use Wegener's determinations of...)
In this book, the authors use Wegener's determinations of the drifting continents as base maps to explain signals for palaeoclimate gleaned from the rock record.
Alfred Lothar Wegener was a German meteorologist, researcher, and geophysicist. He formulated the first complete statement of the continental drift hypothesis.
Background
Alfred Wegener was born on November 1, 1880, in Germany’s capital city, Berlin. His father, Richard Wegener, was a classical languages teacher and pastor. His mother, Anna Wegener, was a housewife. The Wegener family of two adults and five children - Alfred was the youngest - was well-off financially.
Education
Alfred Wegener was an intelligent boy. He received a conventional education at Köllnisches Gymnasium in Berlin, where his academic ability marked him for university education.
He began university in Berlin in 1899 at the age of 18, taking a variety of science classes. He specialized in astronomy, meteorology, and physics.
He began his graduate career in physics and mathematics and attended Planck’s lectures in thermodynamics and thermochemistry. Wegener adopted Planck’s phenomenological approach, his indifference to hypothetical causal mechanisms, and his concentration on the bulk properties of matter - temperature, pressure, mass, and volume. Wegener heeded Planck’s injunction to think of good theory simply as that mode of treating phenomena that corresponded to the state of empirical research at the moment.
In 1902, he began a Doctor of Philosophy degree in astronomy. He spent a year at Berlin’s famous Urania Observatory, whose purpose was to bring astronomy to the public.
Alfred Wegener completed his doctorate in 1905, aged 24. Although now qualified to become a professional astronomer, he was worried that he might not discover anything new or interesting in astronomy. He believed he could make a greater contribution to meteorology - the study of weather and climate.
In 1905, Wegener started work as a scientist at a meteorological station near the small German town of Beeskow.
There, working with his older brother Kurt, he carried out pioneering work using weather balloons to study air movements. If there had been a Guinness Book of World Records in 1906, the Wegener brothers would have won the record for the longest continuous balloon flight ever: 52.5 hours in April of that year.
Wegener was delighted to be appointed as the official meteorologist for the Danmark scientific expedition to Greenland, the world’s largest island, which took place from 1906 to 1908. The expedition’s principal aim was to map Greenland’s unexplored northeast coast. During the expedition, Wegener made his mark by building Greenland’s first meteorological station and taking a large number of atmospheric readings using kites and balloons. The expedition’s work in the uncharted territory was dangerous - three expedition members died of starvation or exposure. He returned there in 1912-1913 and, wintering on a high glacier, completed studies begun on his first visit.
Returning to Germany in 1908, Wegener became an associate professor in meteorology at the University of Marburg. There he quickly gained a reputation for giving lectures that made difficult topics easy for his students to understand. In 1910, he published his first book: Thermodynamics of the Atmosphere. He also had the first inkling of the idea that would bring him both anguish and long-lasting fame: continental drift.
Looking at a world map in 1910, Wegener noticed how the coastlines of eastern South America and western Africa seemed to fit together, rather like jigsaw pieces. After further research, in 1911 Wegener learned that fossils of several species were present in both Brazil and western Africa. This evidence suggested to him that South America and Africa were in physical contact when the fossilized animals and plants were alive. His study of geological data gave him evidence that similar rock formations existed on the two continents.
In 1912, age 32, Wegener delivered talks at German universities and published two papers proposing that Earth’s continents moved. His work on continental drift then suffered two interruptions: a second expedition to Greenland, followed by the outbreak of World War 1 – Wegener was conscripted into the German Army. Nevertheless, while recovering from a wound in 1915, he wrote and published his groundbreaking book: The Origin of Continents and Oceans, in which he discussed the movement of Earth’s continents.
He proposed that many millions of years ago Earth consisted of a single great continent surrounded by ocean. Very slowly the landmasses of this huge continent moved apart to form the continents we see today. Unfortunately, nobody took much notice of his proposal. Today it is clear that Wegener’s ancient continent truly existed. It is called by the name Wegener gave it - Pangaea.
Alfred Wegener took a position as a meteorologist at the German Naval Observatory (Deutsche Seewarte), and in 1921 he was appointed senior lecturer at the new University of Hamburg. In 1920, 1922 and 1929, Wegener published updated editions of The Origin of Continents and Oceans, adding more evidence each time for his idea that the continents move around the planet at very slow speeds. He also added further evidence he had gathered in Greenland, which showed that Greenland and North America were once linked.
He said he was not the first person to propose the movement of continents; others had also found evidence from fossils and rocks which strongly suggested continents now far apart were once joined - the American geologist Frank Bursley Taylor had published evidence in 1910 supporting the idea of continental drift. Wegener’s work was independent of Taylors. In 1920s America, people referred to continental drift as the Taylor-Wegener theory. In 1924 he became a professor at the University of Graz.
Scientists who stray into another field can encounter difficulties, such as those encountered by physicist Luis Alvarez when he proposed a meteor impact had resulted in the extinction of the dinosaurs.
Wegener was an astronomer who had become a meteorologist. He was not a geologist and he found that a large majority of geologists were vigorously opposed to his ideas. In compiling a huge volume of convincing evidence for Pangaea and continental drift he had made one or two small errors, and he also made one big error. Although the rock and fossil evidence he reported should have been more than enough to convince skeptics that his theory was largely correct, Wegener tried to explain why continents move - and got this wrong.
Polflucht is German for pole flight. Wegener proposed that there was a geological force that pushed the continents away from Earth’s poles towards the equator.
Geologists rightly told him this was untrue. Unfortunately, they rejected Wegener’s truly compelling evidence for continental drift. Moreover, they rejected work which today we recognize as a forerunner of the correct explanation of continental drift - plate tectonics, the idea that solid continents float on a fluid mantle.
Wegener published what would be the final edition of his book The Origin of Continents and Oceans in 1929.
(Alfred Wegener's "Entstehung der Kontinente" dispensed wi...)
1915
Views
The idea of continental drift occurred to Wegener in 1910 when he noted the correspondence between the Atlantic shores of Africa and South America. He initially dismissed the idea as improbable. His interest was rekindled in 1911 when he learned paleontological evidence was being used to argue that a land bridge once connected Africa with Brazil.
Wegener became convinced the paleontological and geological similarities required explanation and presented a provisional account of his continental drift theory in 1912. An extended version appeared in 1915 under the title Die Entstehung der Kontinente und Ozeane ("The Origins of the Continents and Oceans") which was not widely read until the third edition appeared in 1924. Wegener was not the first to conceive of continental drift, but his account was the most fully developed and supported by extensive evidence.
Wegener proposed the existence of a supercontinent, which he named Pangaea, surrounded by a supersea, Panthalassa. He believed Pangaea began to split and move apart about 200 hundred million years ago. His strongest supports for the theory were the rocks and the flora and fauna on both sides of the Atlantic. Also, geodetic measurements indicated that Greenland was moving away from Europe. Finally, the separation of Earth's crust into a lighter granite floating on a heavier basalt suggested the possibility of continental horizontal transport.
The most serious problem for Wegener's theory was the lack of a suitable mechanism. It was difficult to imagine a force strong enough to displace the continents through the solid mantle and oceanic crust. Wegener suggested two mechanisms that were later shown to be only one-millionth as powerful as required. By 1928 Wegener's theory had been generally discounted.
Arthur Holmes suggested a viable driving mechanism in 1929. He argued that radioactive heating created convective currents within Earth's mantle, resulting in an internal zone of slippage. The motions thus generated were small but sufficient to account for the displacement of continental landmasses. Holmes' work drew little attention due to the disrepute of continental drift theory.
The discovery of mid-oceanic ridges after World War II renewed interest in Wegener's theory. Paleomagnetic studies in the early 1950s indicated that rocks have magnetic orientations that vary from continent to continent - consistent with continental drift. Wegener's work gained further support in the 1960s with the acceptance of sea-floor spreading and the discovery of subduction zones. Holmes's driving mechanism was then revived and is still widely accepted.
It was eventually recognized that Earth's crust is composed of plates moving relative to each other. Today, plate tectonics is the principal theory of the genesis, structure, and dynamics of Earth's continents.
Quotations:
"Scientists still do not appear to understand sufficiently that all earth sciences must contribute evidence toward unveiling the state of our planet in earlier times, and that the truth of the matter can only be reached by combing all this evidence... It is only by combing the information furnished by all the earth sciences that we can hope to determine 'truth' here, that is to say, to find the picture that sets out all the known facts in the best arrangement and that therefore has the highest degree of probability. Further, we have to be prepared always for the possibility that each new discovery, no matter what science furnishes it, may modify the conclusions we draw."
"It is a strange fact, characteristic of the incomplete state of our current knowledge, that totally opposite conclusions are drawn about prehistoric conditions on Earth, depending on whether the problem is approached from the biological or the geophysical viewpoint."
Personality
Quotes from others about the person
“He was a person of flawless character, unadorned simplicity, and rare modesty. At the same time, he was a man of action, who, in pursuing an ideal goal, achieved the extraordinary by means of his iron will power and tenacity while putting his life at risk." - Hans Benndorf, physicist and seismologist.
Connections
In 1913 Wegener married Else Köppen, the daughter of his former teacher and mentor, the meteorologist Wladimir Köppen. The young pair lived in Marburg. The couple had three daughters Hilde (1914 - 1936), Sophie ("Käte", 1918 - 2012), and Hanna Charlotte ("Lotte," 1920 - 1989).