Place He Was Born and Family Information Alfred Wegners
Alfred Wegener (1880-1930)
"Scientists withal exercise not appear to understand sufficiently that all world sciences must contribute evidence toward unveiling the country of our planet in earlier times, and that the truth of the matter tin only be reached by combing all this evidence. . . It is simply by combing the information furnished by all the globe sciences that we can promise to make up one's mind 'truth' here, that is to say, to find the picture that sets out all the known facts in the all-time arrangement and that therefore has the highest degree of probability. Further, we take to be prepared always for the possibility that each new discovery, no affair what scientific discipline furnishes it, may modify the conclusions we draw."Alfred Wegener. The Origins of Continents and Oceans (4th edition)
Some truly revolutionary scientific theories may take years or decades to win full general credence among scientists. This is certainly true of plate tectonics, one of the most important and far-ranging geological theories of all time; when first proposed, information technology was ridiculed, merely steadily accumulating bear witness finally prompted its credence, with immense consequences for geology, geophysics, oceanography, and paleontology. And the man who starting time proposed this theory was a brilliant interdisciplinary scientist, Alfred Wegener.
Built-in on November 1, 1880, Alfred Lothar Wegener earned a Ph.D in astronomy from the Academy of Berlin in 1904. However, he had e'er been interested in geophysics, and also became fascinated with the developing fields of meteorology and climatology. During his life, Wegener made several fundamental contributions to meteorology: he pioneered the use of balloons to track air apportionment, and wrote a textbook that became standard throughout Deutschland. In 1906 Wegener joined an expedition to Greenland to study polar air circulation. Returning, he accepted a mail as tutor at the University of Marburg, taking fourth dimension to visit Greenland once more in 1912-1913. (The above photo of Wegener was taken during this expedition). In 1914 he was drafted into the High german regular army, only was released from combat duty after existence wounded, and served out the war in the Army atmospheric condition forecasting service. After the war, Wegener returned to Marburg, but became frustrated with the obstacles to advancement placed in his manner; in 1924 he accepted a specially created professorship in meteorology and geophysics at the University of Graz, in Austria. Wegener fabricated what was to be his final expedition to Greenland in 1930. While returning from a rescue expedition that brought food to a party of his colleagues camped in the middle of the Greenland icecap, he died, a 24-hour interval or two after his fiftieth birthday.
While at Marburg, in the autumn of 1911, Wegener was browsing in the university library when he came across a scientific paper that listed fossils of identical plants and animals found on opposite sides of the Atlantic. Intrigued by this information, Wegener began to look for, and find, more than cases of like organisms separated by nifty oceans. Orthodox science at the time explained such cases by postulating that state bridges, now sunken, had once connected far-flung continents. Simply Wegener noticed the shut fit between the coastlines of Africa and South America. Might the similarities among organisms exist due, not to land bridges, but to the continents having been joined together at i time? As he subsequently wrote: "A conviction of the central soundness of the idea took root in my mind."
Such an insight, to exist accepted, would require large amounts of supporting evidence. Wegener found that large-scale geological features on separated continents often matched very closely when the continents were brought together. For instance, the Appalachian mountains of eastern Northward America matched with the Scottish Highlands, and the distinctive rock strata of the Karroo organization of South Africa were identical to those of the Santa Catarina system in Brazil. Wegener as well plant that the fossils plant in a certain identify oft indicated a climate utterly different from the climate of today: for case, fossils of tropical plants, such as ferns and cycads, are found today on the Arctic island of Spitsbergen. All of these facts supported Wegener's theory of "continental drift." In 1915 the first edition of The Origin of Continents and Oceans, a volume outlining Wegener's theory, was published; expanded editions were published in 1920, 1922, and 1929. About 300 million years ago, claimed Wegener, the continents had formed a single mass, called Pangaea (from the Greek for "all the Earth"). Pangaea had rifted, or split, and its pieces had been moving abroad from each other ever since. Wegener was not the kickoff to suggest that the continents had one time been connected, merely he was the first to present extensive testify from several fields.
Modern reconstruction of Pangaea, ca. 255 million years ago -- click to view a much larger version of this map!
Reaction to Wegener's theory was virtually uniformly hostile, and often exceptionally harsh and scathing; Dr. Rollin T. Chamberlin of the Academy of Chicago said, "Wegener's hypothesis in general is of the footloose type, in that it takes considerable liberty with our globe, and is less jump by restrictions or tied down by awkward, ugly facts than most of its rival theories." Part of the problem was that Wegener had no disarming mechanism for how the continents might movement. Wegener thought that the continents were moving through the world'due south crust, like icebreakers plowing through ice sheets, and that centrifugal and tidal forces were responsible for moving the continents. Opponents of continental drift noted that plowing through oceanic crust would distort continents beyond recognition, and that centrifugal and tidal forces were far too weak to motion continents -- i scientist calculated that a tidal force stiff enough to movement continents would cause the Earth to stop rotating in less than one yr. Another trouble was that flaws in Wegener's original data acquired him to make some incorrect and outlandish predictions: he suggested that Due north America and Europe were moving autonomously at over 250 cm per yr (about x times the fastest rates seen today, and almost a hundred times faster than the measured rate for Northward America and Europe). At that place were scientists who supported Wegener: the South African geologist Alexander Du Toit supported it every bit an explanation for the shut similarity of strata and fossils between Africa and South America, and the Swiss geologist Émile Argand saw continental collisions as the best explanation for the folded and buckled strata that he observed in the Swiss Alps. Wegener'due south theory constitute more scattered back up after his death, but the majority of geologists continued to believe in static continents and land bridges.
What prompted the revival of continental drift? In large part information technology was increased exploration of the Earth's crust, notably the ocean floor, beginning in the 1950s and continuing on to the present mean solar day. By the late 1960s, plate tectonics was well supported and accepted by most all geologists. Nosotros now know that Wegener'due south theory was wrong in one major point: continents do not plow through the ocean floor. Instead, both continents and ocean flooring form solid plates, which "float" on the asthenosphere, the underlying rock that is nether such tremendous heat and pressure that it behaves as an extremely viscous liquid. (Incidentally, this is why the older term "continental drift" is non quite accurate -- both continents and oceanic chaff movement.)
Since Wegener'southward day, scientists have mapped and explored the great arrangement of oceanic ridges, the sites of frequent earthquakes, where molten rock rises from below the chaff and hardens into new crust. We now know that the further abroad y'all travel from a ridge, the older the chaff is, and the older the sediments on top of the crust are. The clear implication is that the ridges are the sites where plates are moving autonomously (click on the flick at the left to see a map of the historic period of the ocean crust). Where plates collide, great mountain ranges may be pushed upwardly, such as the Himalayas; or if one plate sinks below another, deep oceanic trenches and bondage of volcanoes are formed. Earthquakes are by far most common along plate boundaries and rift zones: plotting the location of earthquakes allows seismologists to map plate boundaries and depths (click on the movie at the correct to view a map of quake epicenters). Paleomagnetic data take allowed the states to map by plate movements much more precisely than before. It is even possible to measure the speed of continental plates extremely accurately, using satellite technology. Nevertheless, Wegener'south basic insights remain sound, and the lines of evidence that he used to back up his theory are yet actively being researched and expanded.
The images of the body of water flooring on this page were provided by the World Information Center A of the National Geophysical Information Eye/ NOAA.
At that place are a number of excellent WWW sites dealing with the mod theory of plate tectonics. Here is a small sample:
- UCMP'south own Plate tectonics exhibit.
- Plate Tectonics Lesson, from Volcano Globe
Finally, information technology seems appropriate to mention the Alfred Wegener Institute, the German language national inquiry center for polar and marine research, carrying on Wegener'south tradition of interdisciplinary earth scientific discipline.
Source: https://ucmp.berkeley.edu/history/wegener.html
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