Chapter 32 Chapter 29 Continental Drift and Plate Tectonics says:

revolution in earth science The recent revolution in Earth science is remarkable for a number of features that characterize the overall nature of scientific revolutions.But the revolution is also thought-provoking by revealing properties unique to science in our time.Fundamentally, the revolution involved throwing away the traditional idea that continents form, grow, or develop on a fixed base, and introducing the so radical concept that continents "drift" on the Earth's surface with respect to each other and to the ocean floor .A feature of this revolution is its theory of plate tectonics, that is, the Earth's surface is divided into rigid plates, including continents and ocean floors, which drift very slowly relative to each other.

The theory of continental drift was proposed by Alfred Wegener (1880-1930) in an important academic paper in 1912, and was developed and perfected in a monograph published a few years later (1915).The potentially revolutionary nature of this hypothesis was recognized almost immediately, since it required a re-revision of the entire foundations of geography. During the 1920s and 1930s, the idea of ​​continental movement was widely discussed among geographers, and as a result, opposing views were almost unanimous.Therefore, the Earth drift theory proposed by Wegener has been in the stage of what I call a theoretical revolution for a long time. It was not until the middle of the SO s that new evidences were continuously discovered that were more and more favorable to the hypothesis of possible continental movement.But it wasn't until the 1960s that a revolution in Earth science really took place.

Historical analysis shows that this earth science revolution ended a half-century-long state of theoretical revolution only because of the grudging acceptance of a whole set of ideas or theories that had been dormant or had been discarded earlier.This scientific revolution was accompanied by new means of studying the earth and new techniques of disseminating knowledge.Not only are many geoscientists thinking along unconventional lines, but many physicists have also devoted themselves to the study of geosciences and made great discoveries.Thus, the earth science revolution that finally took place was not simply a simple resurrection of the long-resistance theory of continental drift as a fundamental shift in conventional wisdom, but also the creation of a new theory of plate tectonics to describe the simplicity of continental drift. Resurrected, but also created a new theory of plate tectonics to describe the movement of continents.In a sense, Wegener's original theory did not lead to a scientific revolution, but the final scientific revolution did embody the central idea of ​​continental movement in Wegener's theory and the division of the earth's surface into two types of regions (land and the seabed) concept.

One of the most prominent features of this revolution is that geographers working in the discipline generally realize that they are experiencing a revolution in earth science.Many scientists wrote articles or monographs emphasizing the revolutionary nature of the change in the way of thinking about the continents and Earth; they wrote books with catchy titles such as "A Revolution in Earth Science: From Continental Drift to Plate Tectonics" (Haram 1973) or The Grim Years of the Earth Science Revolution (Glenn 1982).The emphasis on revolutionary character is not only characteristic of later historical or critical articles and books, but also of scholarly papers in the era of revolutions in the earth sciences.For example, a rather innovative scholarly paper in Science (Opdike 1966) was entitled "Paleomagnetic Studies of Deep Sea Cores from the South China Sea" and its subtitle was "A Revolutionary Method for Dating Events in Earth's History". In 1970, during a discussion of "a new class of errors", J. T. Wilson claimed that the recent discovery of geomagnetic reversals constituted a "revolution" in Earth science.In the final report (1972) of the "Upper Mantle Project" (U.M.P.) (of the Council of International Scientific Unions), the "unified concept of plate tectonics developed during the implementation of the U.M.P." is said Becoming a "revolution" in Earth science (Schullivan 1974, 343).

This fact was partly reflected in the revolutionary consciousness of the historical reviews and summaries published in the 1970s (mainly by English-speaking scientists); People's acceptance is inseparable from the huge impact of Kuhn's "The Structure of Scientific Revolutions" published in 1962.Thus, Alan Cox (1973), Anthony Hallam (1973), Ursula Marvin (1973) and J. T．Wilson (1973, 1976) specifically mentioned Kuhn when discussing and commenting on recent developments in the theory of continental drift.This scientific revolution is also notable for the series of excellent historical works that appeared in the next decade or so.Many of these works were themselves written by geoscientists, some of whom made fundamental contributions to this revolution themselves.

As a result of examining this recent history, we now know that Francis Bacon was not the founder of a continental conception of movement (Marvin 1973).He merely points out that there is a rough fit between Africa and the west coast of Peru.Nor did Alexander von Humboldt almost two centuries later, by recognizing the similarities between the coastlines on either side of the Atlantic Ocean, go any further to suggest that the two continents were once joined and then separated.However, in 1859, in a fringe book written in French called "Genesis and its Unsolved Mysteries" by the American Antonio Snead-Pellegrini living in Paris, he first proposed the division of the original continent and the Components move the mind.It is also claimed that the Austrian geologist Eduard Suss was an early proponent of continental drift, which, as Marvin (1973) points out, is entirely false.But Seuss did propose in the early 20th century that there were originally two Paleozoic continents, "Atlantis" (in the North Atlantic) and Gondwana (in the South Atlantic).He named the latter Gondwana, which is the region of central India (inhabited by the Gunds).Seuss, like some 19th-century pioneers, believed that our present continents were relics of larger proto-continents, fragments of which had sunk into submarine basins.But he did not propose the break-up process of the original continent, and thus did not establish the idea of ​​continental drift as we understand it today (Marvin 1973, 58).

A more illustrative example is the American geologist F. B．Taylor.In his lengthy paper in 1910, he presented for the first time an internally logical and coherent hypothesis that contained some element of what we understand today as the theory of continental drift (Haram 1973, 3).The hypothesis was first formulated in a pamphlet published in 1898, but Taylor's theory was based primarily on astronomy rather than geography or geology.He hypothesizes that long ago the earth captured a comet that would later become the moon today.This astronomical event increased the rotational speed of the Earth and produced greater tidal forces, which combined to pull the continents away from the poles.In his 1910 paper and in subsequent publications, Taylor further refined his argument for continental motion with geological evidence (Eldrej 1976, 271), but these have not attracted the general attention of the geological community (Marvin 1973, 63-64). In 1911, another American, H. B．Becker pointed out that there is a continental shift caused by cosmic forces including the perturbation of the planets of the solar system (ibid., 65).When Wegener published his work, he summarized the work of many of his predecessors, and included a passage discussing Taylor's contribution in detail.But Wegener twice declared that he "only learned of Taylor's work when the basic outlines of the drift theory had been formed" (ibid., 8-10).In the last edition of this work (1962), Wegener added some new names in the historical review section. In this edition, he wrote: "I am still in F.B. Taylor's 1910 Views very similar to my theory are found in the writings".

Wegener's theory of continental motion Geologists and geophysicists began to seriously discuss the continental drift hypothesis in A.After Wegener's work was published.Judging from his education and personal occupation, Wegener is not a geologist, but an astronomer and meteorologist (his doctoral thesis is on the history of astronomy). Wegener's academic career began in Marburg Obtained a post in astronomy and meteorology, and later a professorship of meteorology and geophysics at Grants (1924-1930), and in his twenties and thirties he continued to make meteorological expeditions in Greenland. In 1930, on the third expedition, he gave his life.According to Lauger Koch, who was on the first expedition with Wegener, the idea of ​​continental drift was formed when Wegener observed the disintegration of ice sheets in seawater.But Wegener himself only said that around Christmas in 1910, he was suddenly struck by the extreme similarity and coincidence of the coasts on both sides of the Atlantic Ocean, and this inspired him to think about the possibility of continental lateral movement.

Apparently, Wegener did not take this idea seriously at the time, but instead considered it "impossible" and gave up (Wegener 1924, 5; 1962, 1).But he did begin building his continental movement hypothesis the following fall.He said that he read "quite by chance" "a summary of the literature describing the similarities between the fauna of the Paleozoic strata of Africa and Brazil" (Marvin 1973, 66).In this abstract, the same or similarity of ancient animal fossils from both sides of the Atlantic Ocean is used to support the then very popular idea of ​​a land bridge between Africa and Brazil.Snakes, for example, apparently cannot cross the vast Atlantic Ocean.Therefore, the discovery of the same or very similar snake fossils on both sides of the South Atlantic proves that there is a considerable possibility of a land passage between South America and Africa long ago.The opposite explanation, which assumes that there are very similar but relatively independent biological evolution processes in most of the land in these two regions, is completely impossible.

Wegener was impressed by the similarity of the fossils, but he disagreed with the hypothesis that the two continents were once connected by some form of land bridge or by a now sunken continent.Because these hypotheses require further explanations for the sinking or disintegration of these lands or land bridges, for which no scientific evidence exists.Of course, there are land bridges between continents, such as the Isthmus of Panama and the Isthmus of Bering, which once existed, but there is no really reliable evidence for ancient land bridges across the South Atlantic.As an alternative theory, Wegener rediscovered his earlier ideas about the possibility of continental drift and, as he puts it, turned out to be purely "fantastical and unrealistic", "without any earth science Meaningful, just a jigsaw puzzle whimsy, rising to a valid scientific concept. Wegener developed his hypothesis further in 1912, citing various supporting evidence, at a geology conference , summarizing and summarizing his results. His first two papers were published later that year. In 1915 he published the monograph "Die Entstehung der kontinente und Ozeane" (Die Entstehung der kontinente und Ozeane). Wegener in In this work, he detailed all the evidence he found to support the theory of continental drift. Revised editions of the work were published successively in 1920, 1922 and 1929, and were translated into English, French, Spanish and Russian. In translation In the English translation (1924) of the third German edition from 1922, Wegener's expression "Die Verschiebung der kontinente" was accurately translated as "continental displacement", but was soon adopted by the commonly used term "continental drift" replaced.

Wegener based his argument on geological and paleontological evidence, not just the high coincidence of coasts, and he emphasized the similarities in geology on both sides of the Atlantic.In the last edition of his work, he cited evidence from paleometeorology. In 1924, he also co-authored a monograph on palaeometeorology with Cobain, from which he deduced that the earth's poles were always moving (see Wegener's articles on geography, geology, biology, palaeometeorology for details). For arguments and evidence in meteorology, palaeontology, see Chapter 2 of Harlan's 1973 book).Wegener believed that in the Mesozoic and continued into the not too distant past.There was a huge total landmass or proto-continent, which he called "Pangaea".This primitive continent later broke up, and the division and displacement of the Pangko fragments gradually formed the pattern of the continents we are in today.According to him, two possible causes of continental drift (or motion, movement) are: tidal forces produced by the moon and "polar drift" forces (pohlflucht), a centrifugal effect due to the rotation of the earth.However, Wegener understood that the real answer to the puzzle of the causes of continental motion was still to be found.He wrote in his book (1962, 66) that the Newton of the theory of continental drift had not yet appeared.How similar these words were to the mentality of Cuvier, Van Tove and others back then.He admits that "the complete answer to the puzzle of drift force may take a long time to find".It now appears that Wegener's most fundamental and creative contribution was his first conception that the continents and the seafloor were two special crusts on the surface that differed from each other in rock composition and altitude.In Wegener's time, most scientists believed that, except for the Pacific Ocean, there was a silicon-aluminum layer on the bottom of the ocean.Wegener's basic ideas were later confirmed by the theory of plate tectonics. Although Wegener's theory of continental drift has been in the stage of theoretical revolution for a long time, this does not mean that his ideas have not attracted attention or have no followers.In fact, that was far from the case at the time! In the 1920s, the international scientific community launched a series of global fierce debates on this issue. On April 16, 1922, an unsigned article was published in the influential "Nature" magazine (vol. 109, p. 200), reviewing the second edition (1920) of Wegener's work.This article summarizes the basic ideas of Wegener's theory in detail, and it is hoped that the English version of this work will be available soon. "Considering the strong objections of many geologists," the authors note, if Wegener's theory is finally confirmed, there will be an "intellectual revolution" similar to the "change in conception of astronomy in the age of Copernicus" ( P. 203). A man named O. Bassin, after hearing a speech by Wegener, wrote an article in the most important German scientific journal "Natural Science" (1921, 219-220) wrote that those who heard Wegener's lectures at the Geographical Society of Berlin were "absolutely overwhelmed" and that Wegener's theory received "universal approval" despite some careful disapproval in ensuing discussions Opinion and well-meaning warning. Bassin concludes: "There is no good reason against Wegener, but more solid evidence must be found before the theory can be accepted unreservedly." " A completely different voice appeared in a review in the August 1922 issue of the British Geological Journal, in which Philip Reich pointed out bluntly that Wegener "was not seeking truth but is justifying a reason while ignoring the facts and arguments against the theory".In the United States, "Geographical Review" published H. F．Read's article, he pointedly pointed out that all the facts he knew were fatal blows to the theory of continental drift and polar migration.In the autumn of the same year, the theory of continental drift also became the subject of discussion and debate at the annual meeting of the British Association for the Advancement of Science.Published by W. B．The annual meeting report written by White described the event as "active and fruitless".However, the "Manchester Guardian" of March 16, 1922 published F, E.Professor Weiss's signed article "Continental Movement: A New Theory".Weiss pointed out that Wegener's theory "is extremely important for geography and geology" and "is also of great benefit to the biological sciences".He concludes that the theory "is an excellent scientific hypothesis that will greatly inspire further inquiry". The main scientific event concerning continental drift in the 1920s was a debate held by the American Society of Petroleum Geologists in Tulsa, Oklahoma in 1926, the conference proceedings "The Theory of Continental Drift: Wegener on the Essays on the Origin and Movement of Terrestrial Lands" was published in 1928.The debate was attended by Wegener himself and F. B．Taylor, among the 11 other attendees, were 8 Americans and 3 Europeans.Chairman of the meeting, Dutch geologist and vice president of Marand Petroleum Company W.Gracht wrote a long preface supporting the theory of continental drift and an afterword refuting opposing views for this collection of essays.These two articles take up more than half of the collection.Some of the participants (C.R. Langeville of Yale University, J. Jory of University College Dublin, G.A.F. Morangraf of Delft University, J.W. Gregory of Glasgow University , Johns Hopkins University's Joseph T. Singerwald Jr.) were deeply skeptical of the theory, but they were tolerant, while others (Stanford's Bailey Willis, University of Chicago's Rollin T. Chamberlin, William Bovey of the United States Coast and Geodetic Survey, and Edward Bailey of Johns Hopkins University vehemently insisted on the contrary geological arguments they put forward, and deliberately used a pseudoscientific Defending themselves against wrong and wrong methods, and sarcastically declaring that their practice was in complete agreement with Wegener's way of thinking and writing. From the point of view prevailing today, one of these criticisms is The hostility and malice are intriguing. It is clear that Wegener has indeed launched a frontal attack on the foundations of earth science and strong traditional belief. The Wegener hypothesis has attracted objections on many fronts.First, it directly contradicts the conventional thinking of almost all geologists and geographers.These people have been educated from the beginning of their lives to the old theory that the continents are stationary and the surface of the earth is fixed.According to the theory of continental drift, there is a relative lateral motion between land masses.This bold idea is as absurd as the Copernican theory in Galileo's time. Second, the new hypothesis holds that the earth is obviously rigid to the most superficial observer, while the fact No. However, Wegener's hypothesis also brought new problems, as geophysicist H. Jeffries and others have long pointed out, continental drift seems to require huge, almost unimaginable power , which far exceeds the tidal force and polar drift force proposed by Wegener himself. The focus of the debate seems to be described in the language of the image: "a fragile land boat sailing on a hard seabed" (see Glenn 1982, 5), the general consensus is that this is clearly impossible. In the history of science, biased accusations against the proponents of new theories, attempts to nip scientific revolutions in their buds, are unfortunately common.Not only was Wegener's method under attack, but because he had no professional diploma, he was not a geologist but a German meteorologist, so he was refused to attend geological conferences, Charlie Schucker, professor emeritus of paleontology at Yale University Te (1982, 140), called the continental drift hypothesis "the German theory", and he quoted P.In the words of Termey (Director of the French Geological Survey): Wegener's theory is only "a beautiful dream, the dream of a great poet", and when people try to embrace it, they will find that "all he gets is a pile of foam and A wisp of smoke".Moreover, in Schuckert's view, "Wegener's generalizations are too hasty to take into account the whole history of geology" (p. 139), he is just an outsider, a person who has done nothing in the field of paleontology or geology. people who actually work.Schucker concluded: "A layman who transplants the facts he has mastered from one discipline to another will obviously not get the correct result". Wegener was rejected - at least in part because he was not a member of the geological "club", as has been documented.H. Jeffries, in attacking Wegener's theory, evidence and scientific method, declared that "Wegener was basically a meteorologist." 1944, Chester R.Langeville hypocritically stated in an article in the American Journal of Science (vol. 242, p. 229): "The kind critics pointed out" that Wegener's inconsistencies and omissions "can be tolerated , because he is not a geologist".What's more, until 1978, George Garrod Simpson (1978, 272) repeated his earlier view that "most of Wegener's paleontological and biological evidence is either ambiguous or Totally wrong." He accused Wegener (the "German meteorologist") of daring to venture into a field in which he "had no first-hand knowledge". In the 1930s and 1940s, most geologists shared the views expressed by Jeffreys in his influential book Earth, 3rd Edition (1952): "The defense of continental drift in the 1930s, No testable theory has been produced".Conservative geologists and paleontologists have even used the idea of ​​continental drift as a "joke" in the classroom.Harvard professor of paleontology Percy E.Raymond, telling his students that half of the Devonian phylabranchs were found in the United States and the other half in Ireland.These two parts "correlate fairly well" and must therefore be "two halves of the same Axonidae, which was divided in two by Wegener's hypothesis in the Pleistocene" (Marvin 1973, 106) . However, in the 1920s and 1930s, there were many people who supported Wegener.Reginald A. of Harvard University.Daly subscribed to the basic idea of ​​continental drift, although he was not strictly a Wegenerian, and he himself once said that Wegener was "a German meteorologist".Daly proposed his own theory of continental motion, which now appears to be somewhat "closer to the door of the current model of plate tectonics" (Marvin 1973, 99).On the title page of his book "Our Earth in Motion" (1926), Daly wrote "Eppursi Muove" - ​​this is when Galileo was forced to abandon the Copernican theory of earthquakes he had always believed in. A justification that was said. ("Eppursi Muove" means "Earth is still in motion"). In the 1920s, one of the main proponents of Wegener's views was Emile Argond, the founder and director of the Neuschatt Geological Institute in Switzerland. In 1922, at the first International Geological Conference after World War I, Argond bravely stood up to support the basic idea of ​​"Asian plate tectonics" proposed by Wegener. Argond not only collected and organized There are a large number of arguments supporting Wegener's theory, and useful work has been done in dividing the boundary between Wegener's "movement theory" and the traditional "fixation theory".He declares that "fixation theory is not a theory but a negative patchwork of several crude theories" (Argond-Karoz 1977, 125).Although Agonde definitely agrees with the "motion theory" and lists abundant and detailed evidence to support this theory, he has to admit: "We still know nothing about the forces that produce continental drift" (p. 162 ). The two main proponents of Wegener for the age were Arthur Holmes (considered by many to be "the greatest British geologist of this century") (Haram 1973, 125) and the South African geologist Alexandre du Toit. When the 1928 collection of essays on continental drift in the United States was published, Holmes accepted the theory of continental drift and published an article reviewing the collection in the September 1928 issue of Nature.In his article he states: "All objections ... are directed primarily at Wegener himself and not at his basic views".He also noted that "when it seemed that all was said and done, then came stronger evidence for continental drift than Taylor and Wegener had presented." Not only did Holmes accept the general view of continental motion And became the main defender of the theory of continental drift in Britain, and he also proposed a new mechanical reason for drifting motion.According to him, the convective movement of lava in the mantle (the part of the Earth immediately below the crust) would lead to the formation of mountains and the drift of continents (Marvin 1973, 103; Hallam 1973, 26).Du Toit lived in Johannesburg and, as Ursula Marvin (1973, 107) reminds us, "lived in the center of the ancient continent of Gondwana, which has the best evidence of drift," in a His views are summarized in a book entitled Our Wonderful Earth (1973) (subtitled "The Continental Drift Hypothesis").Dedicated to the book, "In Memory of Wegener and others who have made outstanding contributions to our geology of the earth," du Toiter presents a theory of the earth that differs slightly from Wegener's (See Marvin 1973, 107-110; Hallam 1973, 30-36). For example, du Toit proposed that the proto-continent did not have only one—Pongo, as Wegener suggested—but two Two, namely "Laurosia in the northern hemisphere and Gondwana in the southern hemisphere". Du Toit attributed the opposition to Wegener's hypothesis to two factors: one was the lack of a satisfactory mechanical mechanism for drift; one of the features.However, du Toiter is well aware that accepting continental drift means "rewriting all our textbooks, not only those of geology, but also those of palaeogeography, palaeometeorology, and geophysics" (P. 5).He said that there is no doubt that "the drift theory embodies a great and fundamental truth", while Taylor and Wegener put forward a "revolutionary" hypothesis (p. Vii). Du Toit was not alone in seeing Wegener's theory as "revolutionary". Author on "Natural Science" magazine in 1921, unsigned reviewer on "Nature" magazine in 1922, F. E．Weiss, 1926, van der Gracht, and a number of other friends and foes, have used the term.Daly (1926, 260) described the theory of continental drift as a "new astonishing explanation", which many geologists considered too bizarre, even astonishing, a "revolutionary idea".Philip Reich also hinted at the novelty and revolutionary nature of Wegener's ideas when he noted that "the motion of the land is to us what the motion of the earth was to our ancestors" (1922, 338).In a 1928 review of the Tulsa Papers in the Journal of Geology, Reich explicitly used the term Wegener's "revolutionary theory." Wegener himself was well aware that his new ideas were potentially revolutionary. In 1911, a year before he published his new ideas publicly, Wegener wrote to his colleague, teacher W.Cobain.Why, he writes, are we "hesitant to let go of old ideas?" "Why do people try to hold back a new idea for ten or thirty years? Maybe because it's revolutionary?" 's rhetorical question is accompanied by a bold and simple answer: "I don't think old ideas will last more than ten years"! Due to the revolutionary nature of the theory of continental drift, stronger than usual evidence was required for the theory to gain consensus among scientists.For any radical or radical change to be accepted by the scientific community, there must either be impeccable or irrefutable evidence, or a clear superiority over all existing theories.Obviously, in the 1920s and 1930s, Wegener's theory did not meet the above two conditions.In fact, no evidence of this "airtightness" was found until after the 1950s.Moreover, accepting Wegener's views meant that the entire science of geology had to be radically restructured.Obviously, in the absence of irrefutable evidence, people are of course reluctant to do so.University of Chicago geologist R. T．In the Proceedings of the 1926 meeting of the American Society of Petroleum Geologists, Chamberlin wrote that at a meeting of the Geological Society of America in 1922 he had heard it said: "If we accept Wegener's hypothesis, we will All the knowledge of the past seventy years has to be unlearned and everything started from scratch.” Now it seems that this statement is completely true.We should note that Chamberlin's words were repeated forty years later in a different sense. In 1968, Tuzzo Wilson (1968a, 22) wrote in a book: "Since the earth is indeed an active celestial body moving in a slow manner, we must regard it as basically stationary If so, then we must completely revise all our previous theories and all textbooks, start from a brand new concept, and establish a brand new science." Hallam (1973, 110), in attempting to explain why Wegener did not provide a satisfactory mechanical mechanism for continental drift—which is generally regarded as "the greatest obstacle to the acceptance of Wegener's hypothesis"—points out that "gravity Theory, magnetism, and electricity were generally accepted long before satisfactory explanations were found." In geology, he added, the lack of consensus on "potential causes" did not prevent "previous The existence of ice ages" is a generally accepted hypothesis.However, J. T．Wilson (1964, 4) argues that "people are not always ready to admit the existence of a phenomenon (such as the geomagnetic field) or process (such as a storm) until they have been satisfactorily explained." On this point, Some further clarification should be made. R．Laudan wisely points out that the question of the "mechanical mechanisms" of continental drift is very different from "the theory of gravity, geomagnetism and electricity" or "the existence of storms."In continental drift, the problem "is not simply the lack of mechanical mechanisms or causes," (Laudan 19782; Gutting 1980, 288) but "all conceivable mechanical mechanisms that seriously impinge upon the theory of physics." Moreover, theories about the earth and its internal natural phenomena have been established and widely accepted by people, and they can perfectly and reasonably explain most of the observed phenomena. S． K．Rankine (1980, 193) found through research that although in the 1950s or earlier, "it is generally believed that the lack of mechanical mechanisms is the main obstacle to the acceptance of geological or paleontological evidence for continental drift," but today , "the theory of plate tectonics has been accepted without a generally accepted physical mechanism." He pointed out around 1980 that "the problem of the mechanical nature of plate motion" is "the most difficult problem facing contemporary geophysicists." important challenge." Modification of Wegener's Theory Now, since we have witnessed the whole process of this revolution, it is easy to see that there are two fundamental breakthroughs that distinguish the two stages of the theoretical revolution from the current revolution.The first breakthrough was the accumulation of new and convincing evidence of relative motion between the continents and the ocean floor.The evidence is more consistent than that of the coastline.It is even far superior to the conformity of geology and ecology on both sides of the ocean, as well as the similarity of plant and animal fossils.The second breakthrough was a fundamental restructuring of the theory that resulted in a major change in basic ideas and raised the question whether the revolution that was finally accomplished could justly be seen as the revolution that sought to achieve Half a century without a successful revolution?This situation has many parallels with the so-called Copernican revolution.This revolution, promoted by Galileo and Kepler and finally completed by Newton, only retained the most general astronomical concept of Copernicus, that is, the concept that the earth moves while the sun is stationary, and abandoned the basic concept of Copernican cosmology. feature.Likewise, the revolution in Earth science retained only Wegener's most general idea that continents could have mutual motion, while abandoning the fundamental feature of Wegener's theory - continents composed of silicon alone or separately on oceanic crust motion, while the denser layers of the oceanic crust are stationary. The current latest point of view is this: the huge plates covering the earth's surface are moving, and some of the plates will drive the continents or parts of the continents to move together with the seabed.Thus, the theory of the movement of whole continents was replaced by a different theory.The new theory suggests that land movements are nothing more than the appearance of violent movements within the Earth's crust.In the process of this causal connection, the "polar drift force" and "tidal force" listed in Wegener's hypothesis become meaningless. New evidence in the 1950s first came from studies of paleomagnetism and geomagnetism.Paleomagnetism is the study of magnetism in "residual flower" rocks, that is, magnetism that remains in solidified lava samples.This magnetism is left in rocks containing iron oxide due to the influence of the Earth's magnetic field.London's P. M． S．Blackett and Cambridge University's S. K．Research by Rankine and others showed that the Earth's magnetic field was never constant but varied, and even experienced north-south inversions.The way it changes has a close relationship with time, and this relationship can be determined (these studies were made possible by the advent of highly sensitive magnetometers, of which Blackett was the main inventor).When the path of movement of the magnetic pole position is carefully traced, it will be found that the movement and change of the magnetic pole differs from region to region, indicating that each land mass is moving independently.相关证据还揭示出地球南部各陆地聚集在南极地区形成一个原始大陆——冈瓦纳大陆的时间，因此，这些组成部分说明我们现在的各个大陆肯定存在着某种横向运动（见麦肯奇1977，114-117）。 沿着这条研究线索所获得的第一批成果，地球科学界没有立即接受大陆移动的存在；无疑，关于地球磁场演化史的细节尚有太多的没有解决的难题。而关于磁机制的见解"过于复杂深奥，其中还存有许多未经检验的假说"（麦肯奇1977，116）。但是，主要是在地球物理学家中对此产生了极大的兴趣。1956年，地学一本以大陆漂移为主题的论文集出版了，澳大利亚国立大学的E．埃尔温对过去几年的磁机制研究作了回顾与评述，最后他总结道："各种证据对此后的结果，倾向于对地球磁轴相对于地球本身发生过位置变化的观念以及各大陆相互之间有漂移运动的观念有利"（埃尔温1953；1958，见马文1973，150-152）。 推动魏格纳的基本思想（而非魏格纳理论本身）复兴的第二条研究线索是关于海底山脉的研究。海洋和内陆湖泊大约覆盖了地球表面的70％。由于关于海底的特征与本质的知识在本世纪30-40年代还相当粗浅，因此，我们容易理解为什么战前关于大陆漂移的争论最终没有定论（哈拉姆1973，37）。然而，有关大西洋底的地形图早已存在，1916年，泰勒就曾指出，大西洋两边的陆地好像是从海底山脉两侧慢慢升起的。魏格纳本人也通过密度、磁性、成份等方面的分析，指出海底是玄武岩构成的，但没有人对此予以注意。我们目前关于大陆运动的直接线索来自对海底世界的研究。在国际地球物理年（1957－1958）期间，在测量地球引力和相关地震-引力数据方面，已经有了全新的技术。地球物理学家找到了测定通过海底的热流速率的方法，这些研究的一般结论是：巨大的海洋壳层岩石块确实能够"相互之间明显地移动一大段距离"（哈拉姆1973，52）。这些研究成果与来自磁机制研究获得的发现不谋而合，都强有力地支持大陆之间经历了相互运动的观点。到这时为止，大陆漂移理论才正式由于板块构造说的广泛被接受而得以完善。板块构造说是一个结构系统，按照这种学说，地壳像"大板块的拼图，用形象的比喻就如巨大的大块浮冰或铺路石。"这些板块独立地运动着，边缘与别的板块碰撞则会发生变形。马文特别强调说："运动的板块不像魏格纳所设想的那样是大陆，也不是整块的海底壳层"（1973，165）。既然每一板块既包括陆地部分也包括海底部分，那么板块的运动和魏格纳大陆运动的概念，便相去甚远了。因此，由于最初的"大陆漂移"术语，含有整块大陆运动的意味，它不再是严格精确的了（哈拉姆1973，74）。1968年，人们提出六大板块和十二个小板块覆盖地球的观点。从那时起，有关板块构造学说的理论细节越来越充实了。 海底扩张说 为了完满地解释地壳的不稳定性和可变性，板块构造理论还必须与"海底扩张说"结合起来。海底扩张说是普林斯顿大学的哈里·赫斯于1960年首次提出来的。该学说描述的是纵贯主要大洋海丘两侧的海底部分持续受到挤压的过程。赫斯最初是在1960年撰写的一篇手稿中阐述这个观点的，而该手稿作为一本书中的一章直到1962年才正式出版。由于这个观点极为新颖、奇特，以致于赫斯把书中的这一章看作是"一篇地球散文诗"。赫斯指出，逐渐降到海底的巨大海丘是地壳下地幔内熔融物质上涌的出口。这种物质同样沿着海丘的两侧流淌、冷却、固化，最后变成地壳的一部分覆盖在原来的地壳之上。当海丘两侧的地壳以这种方式积累增长时，这种物质（巨大的板块）就会横向离开海丘。既然地球不可能增大，这个板块在增长过程中也不会简单地扩张，那么在远离诲丘之外，必定会有一处板块发生分裂。换言之，板块离海丘最远处的边界被挤到另一个板块底下，并最终进入地幔中。这时，板块边缘的水分全部被挤压出来，而板块进入地幔的部分又重新变成了熔融状。这个过程同某种对流"传送带"联系在一起，即从海丘的地幔中带出物质，然后把它传送出去，这些物质最终在远处的海沟附近又再次回到地幔中。 于是，大西洋底便产生了一股巨大的、持续的压力，它把载有南美洲和非洲的两大板块推离大西洋中的海丘。大约在1．8亿年以前，南美洲和非洲是连在一起的，这就是冈瓦纳大陆。两块大陆的分裂线与导致海底扩张的，并且现在仍很活跃的大西洋底海丘线十分吻合。每当发生地震时，这条海丘线便清楚地显现出来，目前，它与南美洲和非洲的大西洋海岸线的距离大致上是相等的。 赫斯进而提出了海底扩张说的合理推论。他认为，由于海底扩张效应，海底壳层不断地在大陆一边创生，而同时又在大陆的另一边消失（麦肯奇1977，117）。这个观点通常被看成板块构造说进一步发展的主要内容，也是我们理解大陆漂移理论的主要基础。大西洋地壳层从海丘移出的速度大约是每年四厘米。按照这个速度推算，大西洋海底壳层从海丘全部移出，也就是移动整个大西洋宽度的距离所需的时间为两亿年。这个数字立即可以用来解释许多未知的奥秘。例如，海底钻孔找到的化石标本都未超过两亿年（中生代前后）。而从陆地上挖掘出的海生化石研究表明，这些海生生物都可追溯到二十亿年以前。再如，假设海床的年龄与大陆同样古老，那么按正常的沉积速度，海床上应当产生很厚的沉积层，但钻探分析表明，海床上的沉积物很少。简而言之，在海洋存在的几十亿年中（乌耶达1978，63），海底并不是永恒的，而是在不断地变化，不断地运动。 如果把赫斯的观点同板块构造说的一般思想结合起来，就可以满意地解释另一个现象或过程；板块边缘新物质的增加，并不使板块的面积增大。由于压力作用，板块在不断地缩小。这一点在两个板块的碰撞处山脉的形成和山脉的更替中，表现得非常明显。 哈里·赫斯在阐述他的海底扩张说时，很清楚他的理论"与大陆漂移说并不完全相同"（1962，617）。按照大陆漂移说的思想，"大陆…受某种未知力的驱动，在海底壳层上漂移"，但他的理论的基本思想是，大陆"被动地浮在地幔之上，当地幔物质从海底海丘上流出时，大陆便横向移动开来。" 前面曾谈到，一般人都认为：最初的纯粹古磁学证据并不能完全说服大多数地球科学家放弃"大陆固定观"。决定性的证据来自新的磁机制的研究，它戏剧性地证实了海底扩张说。船载磁测仪揭示出海底壳层条状磁化区域的存在（休莱1959，61）。如果赫斯的解释是正确的，那么在海丘两侧就应该有对称的条状磁化区域。这项验证性实验是剑桥大学当时的研究生F． J．维恩和他的导师P． H．马修斯提出的。实地测量很快证实，条状磁化区域确有预期的那种对称性。 按照这一理论，当炽热的熔融物质沿海底海丘流淌并固化时，它便感应了当时的地磁场。既然新的物质把它从海丘上推开，它仍将保持冷却时所感应的磁性。因此，每一条前后相继固化的物质带应该有记录形成日期的磁性标志，而海丘两侧同时对称形成的物质带也因此具有相同的磁性方向。1963年，维恩和马修斯在《自然》杂志上发表了这一重要假说，这个假说翌年就通过了实验（实测）检验。事实上，地球磁场演化的历史不仅表现出一些微小的变化，而且在目前已知的年代中还经历过南北逆转。所有这些，都是在实测和研究海底海丘两侧的条状磁化带过程中发现的。 虽然这个假说今天听起来非常具有逻辑性，一点也不令人惊奇，但在当时看来却是异常激进而大胆的。维恩回忆说，当他第一次把他的观点告诉剑桥大学地球物理学家莫里斯·希尔时，尽管希尔"很有礼貌的一声不吭，只是看着我并且谈些别的事情，但他一定在想我今天疯了"（格伦1982，279）。维恩还把他的假说告诉了爱德华·布拉德爵士，即使布拉德爵士"这有点大胆猜测的味道"，但他却对此持"非常积极的鼓励和赞赏的态度"。维恩"非常渴望能和特迪（爱德华的爱称）·布拉德共同发表这个观点，"因为他觉得他们俩的名字并列在一起，"布拉德和维恩看起来很了不起"。但特迪非常直率地拒绝了，他不想让他的名字出现在这篇论文上。布拉德是地球物理学界一位著名的革新家，他对地球热流理论作出过重要的贡献。他善于接受新思想，"以极大的热情接受了这个假说并以高度赞赏的态度四处传扬"。他只是不愿意在一开始就接受维恩的请求成为合作者（p．358）。 维恩和马休斯提出的假说（加拿大的劳伦斯·莫雷也曾独立地提出过，详情见1982，271）"堪与本世纪地球科学中的任何成就相媲美"（p．271）。它不但能确定无疑地证实赫斯的海底扩张说，而且还能推算出扩张的速度。推算方法是基于一种独立的、由地磁场倒置所标定的精确的时间尺度。看来，人们普遍赞同这样的看法：维思-马休斯-莫雷假说的确证，触发了地球科学的"革命"。在这些突破性成就的基础上，下一步要做的工作便是："建立全球构造的新理论，重构地球知识的新体系"（哈拉姆1973，67）。 革命地位的确立 凡是研究过地球科学最近刀年发展史的人（如上述舒利文1974，特别是格伦1982）都会认识到，要最终完成这样一场革命，还有多少重要的工作有待完成。在前面的论述中，我只是介绍了几位最著名人物的杰出贡献。关于爱德华·布拉德、图佐·威尔逊、莫里斯·欧文以及其他一些科学家的重要工作，我几乎没有提及。长期以来，许多著名的地球物理学家不但拒绝接受板块构造理论，也拒绝接受海底扩张说的基本思想。被《自然》杂志誉为"苏联最伟大的地球物理学家"的弗拉基米尔·贝洛索夫1970年宣称："海底扩张说没有一个方面能经得住批评"（舒利文1974，IOS）。12年后的1982年12月，年届91岁高龄的哈罗尔德·杰弗里斯爵士在《皇家天文学会地球物理杂志》（vol。71，555－556）上发表文章，仍然以不屑一顾的口吻，把"海底板块的错动"比作"用黄油做的刀切黄油"。60年来，杰弗里斯一直是反对大陆漂移说的主要代表人物。 地球科学界的保守主义除了托依特提到的之外，在权威性的《科学家传记辞典））1976年版中也得到了印证。在该辞典中，魏格纳的条目（vol．14，214-217）是澳大利亚悉尼大学的K． E．布伦撰写的。他在这篇文章的结论部分，不大情愿地提到了倾向于支持魏格纳观点的证据（来自古磁学和海底壳层研究）。但紧接着，他罗列了一大堆"反对大陆漂移说"的新旧批评意见。布伦写道：当"该理论的创立者们就这些批评意见作出答复后，这些答复也受到了质疑"（p．216）。 1976年，也就是哈拉姆和马文的历史研究著作（二者都宣称地球科学革命已经取得了成功并分析了它的结构）出版三年后，当时这篇最新的魏格纳传记的最后结论是："大多数地球科学家的热情，甚至是宗教式的狂热，促使他们相信大陆漂移理论已建立起来了"（p．217）。 布伦使用"宗教式的狂热"这种说法，是因为60年代观念变化时期所使用的语言带有很强的宗教隐喻色彩，在涉及到转变问题时更是如此。库恩通过研究发现，这一点是科学革命过程中相当普遍的特点之一。图佐·威尔逊的经历便是一个典型的例子。威尔逊在1959年还是大陆漂移说的主要反对者之一。但没过几年，他的观念发生了转变，并自称是"改造了的反大陆漂移说者"（见威尔逊1966，3－9，谈及了他的转变过程）。后来，他不仅提出了一些支持大陆漂移说的重要的地质学证据，而且还成为地球科学革命的主要先驱之一。1963年，国际地质学和地球物理学联合会第13次会议在美国伯克利举行。在会后出版的关于"上地幔计划"的文集中，威尔逊发表文章勇敢地宣布："地球科学中已经在孕育一场伟大的科学革命"（塔克奇1970，244）。他说，地球科学目前的情境正同"哥白尼和伽利略的观念被接受前天文学的情境；分子和原子概念引入以前化学的情境；进化论建立之前生物学的情境；量子力学诞生前物理学的情境"一样。 60年代末70年代初，出现了大量关于大陆漂移说。古磁学和地磁学的论文集。1968年4月，美国哲学学会年会文集便是其中之一，其标题为《重游冈瓦纳大陆：大陆漂移说的新证据》。该文集收录了这样一篇文章：《静止还是运动的地球：当前的科学革命》。文章作者威尔逊（1968，309；317）宣称："我们这个时代发生的这场伟大的科学革命应当称作魏格纳革命"，以纪念这场革命的"主要倡导者"。地球科学家们一般都赞同威尔逊的意见，认为确实存在一场科学革命，作为首先提出大陆漂移说的关键人物魏格纳理应获得这一殊荣。可是，历史上以个人名义命名革命的荣誉曾经赋予给哥白尼、伽利略、牛顿、拉瓦锡、达尔文和爱因斯坦，但至今仍未赋予魏格纳。 正如我们已经看到的那样，许多文献的作者把魏格纳开创的科学革命比作哥白尼革命。二者有一点是极为相似的：地球科学中最后的革命与魏格纳最初的假说已相去甚远，而开普勒、伽利略和牛顿最终建立起的体系中，与哥白尼的理论一样大相径庭。正如天文学革命直到哥白尼的著作1543年发表半个多世纪后才最终到来一样，地球科学革命也是在魏格纳最初的论文与著作发表50年后才得以发生。最终发生的所谓哥白尼革命，实际上是牛顿革命，这场革命主要基于伽利略、开普勒的成就，而作为这场革命基础的"哥白尼体系"最终成为了开普勒体系。与此相似的是，本世纪60年代发生的地球科学革命并没有体现魏格纳的理论，而只是体现了其学说所蕴含的基本思想，即在地球的全部演化史中，大陆并非一直固定在现在其所处的位置上，在历史上的某个时期，它们曾聚集在地球的两极。魏格纳的主要贡献是首次提出了大陆运动的思想，它在地球科学革命中的地位正如哥白尼的主要贡献——指出可以按照地球运动而非静止的观念构造一个新的宇宙体系——在天文学革命中的地位一样。 地球科学从固定观到运动观，特别是向大陆漂移说和板块构造说的飞跃，根据第3章提出的四项主要的检验标准，无疑是一场革命。首先，传统地质学观念发生的这种变化在当时就被许多观察家包括这一领域的实际工作者看作是一场革命。我认为，这是发生科学革命的主要标志。其次，考察1912年以前和1970年以后的地球科学的内容表明，量的变化也足以构成一场科学革命。第三，严肃的科学史家们也断言；地质学思维方式的变革足以引发一场科学革命。很明显，这有点主观臆断的意味，但它确证了参与这场革命的地质学家和地球物理学家的结论。我们已经看到，在成功的地球科学革命发生以前很久（即理论科学革命阶段以前），很多地质学家甚至那些魏格纳学说的反对者们都意识到了大陆漂移说的革命性，并且完全懂得如果接受了这种观点，对全部的传统地质学理论来说将意味着什么。第四，当今地质学家们普遍认为，他们的学科已经发生了一场革命。 但是，这场革命的程度如何？它能称得上是一场堪与达尔文革命、量子力学革命和相对论革命或是牛顿革命相比的重要的科学革命吗？或者是规格稍逊一筹的，与化学革命类似的革命吗？我们已经看到，乔治·G．辛普森把它称为"一场重要的亚革命（Sub-revolution）"。 D． P．麦肯奇（1977，120-121）在一篇文章《论板块构造说与地质学理稻进化"的关系》的中，把"板块构造说对地球科学的冲击"与"DNA结构的发现对生物学的冲击"作了对比。他的结论是："板块构造说与导致分子生物学创立的那些发现相比，是一场不太具备根本性质的革命"，正是由于这个原因，"这一新思想…已经被地质科学所同化并迅速地加以发展。 "但对任何局外人来说，如果了解到我们关于地球演化史观念发生的根本性变化，必然会感到观念的飞跃是如此巨大，简直就是一场伟大的革命。只是由于完全缺少意识形态成份，这场革命才显得不那么壮观。