12 THE EARTH MOVES

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    IN ONE OF his last professional acts before his death in 1955, Albert Einstein wrote a shortbut glowing foreword to a book by a geologist named Charles Hapgood entitled Earth’sShifting Crust: A Key to Some Basis of Earth Sce. Hapgood’s book was asteady demolition of the idea that tis were in motion. In a tohat all but ihereader to join him in a tolerant chuckle, Hapgood observed that a few gullible souls hadnoticed “an apparent corresponden shape betweeain tis.” It would appear,he went on, “that South America might be fitted together with Africa, and so on. . . . It is evenclaimed that roations on opposite sides of the Atlantic match.”

    Mr. Hapgood briskly dismissed any suotions, noting that the geologists K. E. Casterand J. C. Mendes had doensive fieldwork on both sides of the Atlantid hadestablished beyond question that no such similarities existed. Goodness knows what outessrs. Caster and Mendes had looked at, beacuse in fact many of the roations onboth sides of the Atlanticare the same—not just very similar but the same.

    This was not ahat flew with Mr. Hapgood, or many eologists of his day. Thetheory Hapgood alluded to was one first propounded in 1908 by an amateur Amerigeologist named Frank Bursley Taylor. Taylor came from a wealthy family and had both themeans and freedom from academistraints to pursue unventional lines of inquiry. Hewas one of those struck by the similarity in shape between the fag coastlines of AfridSouth America, and from this observation he developed the idea that the tis had onceslid around. He suggested—prestly as it turned out—that the g together oftis could have thrust up the world’s mountain s. He failed, however, to producemu the way of evidence, and the theory was sidered too crackpot to merit seriousattention.

    In Germany, however, Taylor’s idea icked up, and effectively appropriated, by atheorist named Alfred Wegener, a meteist at the Uy of Marburg. Wegeneriigated the many plant and fossil anomalies that did not fit fortably into the standardmodel of Earth history and realized that very little of it made sense if ventionallyinterpreted. Animal fossils repeatedly turned up on opposite sides of os that were clearlytoo wide to swim. How, he wondered, did marsupials travel from South America to Australia?

    How did identical snails turn up in Sdinavia and New England? And how, e to that,did one at for coal seams and other semi-tropical remnants in frigid spots likeSpitsbergen, four hundred miles north of Norway, if they had not somehow migrated therefrom warmer climes?

    Wegener developed the theory that the world’s tis had one together in asingle landmass he called Pangaea, where flora and fauna had been able to mingle, before thetis had split apart and floated off to their present positions. All this he put together in abook called Die Entstehung der Koe und Ozeane, or The in of tis andOs, which ublished in German in 1912 ae the outbreak of the FirstWorld War in the meantime—in English three years later.

    Because of the war, Wegener’s theory didn’t attract muotice at first, but by 1920, whenhe produced a revised and expanded edition, it quickly became a subject of discussion.

    Everyone agreed that tis moved—but up and down, not sideways. The process ofvertical movement, known as isostasy, was a foundation of geological beliefs feions,though no one had any good theories as to how or why it happened. One idea, which remainedibooks well into my own school days, was the baked apple theory propounded by theAustrian Eduard Suess just before the turn of the tury. This suggested that as the molteh had cooled, it had bee wrinkled in the manner of a baked apple, creating obasins and mountain ranges. Never mind that James Hutton had shown long before that anysuch static arra would eventually result in a featureless spheroid as erosion leveledthe bumps and filled in the divots. There was also the problem, demonstrated by Rutherfordand Soddy early in the tury, that Earthly elements hold huge reserves of heat—muuch to allow for the sort of cooling and shrinking Suess suggested. And anyway, if Suess’stheory was correct then mountains should be evenly distributed across the face of the Earth,which patently they were not, and of more or less the same ages; yet by the early 1900s it wasalready evident that ses, like the Urals and Appalas, were hundreds of millionsof years older than others, like the Alps and Rockies. Clearly the time was ripe for a heory. Unfortunately, Alfred Wegener was not the man that geologists wished to provide it.

    For a start, his radiotions questiohe foundations of their discipline, seldom aive way to gee warmth in an audience. Such a challenge would have been painfulenough ing from a geologist, but Wegener had no background in geology. He was ameteist, foodness sake. A weatherman—a Germaherman. These were notremediable deficies.

    And so geologists took every pain they could think of to dismiss his evidend belittlehis suggestions. To get around the problems of fossil distributions, they posited a “landbridges” wherever they were needed. When an a horse named Hipparion was found tohave lived in Frand Florida at the same time, a land bridge was drawn across theAtlantic. When it was realized that aapirs had existed simultaneously in SouthAmerid Southeast Asia a land bridge was drawn there, too. Soon maps of prehistoricseas were almost solid with hypothesized land bridges—from North America to Europe, fromBrazil to Africa, from Southeast Asia to Australia, from Australia to Antarctica. Theseective tendrils had not only vely appeared whe was necessary to move aliving anism from one landmass to another, but then obligingly vanished without leaving atrace of their former existenone of this, of course, was supported by so much as a grainof actual evidehing s could be—yet it was geological orthodoxy for the half tury.

    Even land bridges couldn’t explain some things. One species of trilobite that was wellknown in Europe was also found to have lived on Newfoundland—but only on one side. Noone could persuasively explain how it had mao cross two thousand miles of hostileo but then failed to find its way around the er of a 200-mile-wide island. Even moreawkwardly anomalous was another species of trilobite found in Europe and the Pacifiorthwest but nowhere iween, which would have required not so much a land bridge as aflyover. Yet as late as 1964 when the Encyclopaedia Britannica discussed the rival theories, itwas Wegener’s that was held to be full of “numerous grave theoretical difficulties.”

    To be sure, Wegener made mistakes. He asserted that Greenland is drifti by about amile a year, which is clearly nonsense. (It’s more like half an inch.) Above all, he could offerno ving explanation for how the landmasses moved about. To believe in his theory youhad to accept that massive tis somehow pushed through solid crust, like a plh soil, without leaving any furrow in their wake. Nothing then known could plausiblyexplain what motored these massive movements.

    It was Arthur Holmes, the English geologist who did so much to determihe age of theEarth, who suggested a possible way. Holmes was the first stist to uand thatradioactive warming could produce ve currents within the Earth. In theory thesecould be powerful enough to slide tis around on the surface. In his popular andiial textbook Principles of Physical Geology , first published in 1944, Holmes laid outa tial drift theory that was in its fuals the theory that prevails today. It wasstill a radical proposition for the time and widely criticized, particularly in the Uates,where resistao drift lasted lohan elsewhere. One reviewer there fretted, without anyevident sense of irony, that Holmes presented his arguments so clearly and pellingly thatstudents might actually e to believe them.

    Elsewhere, however, the heory drew steady if cautious support. In 1950, a vote at theannual meeting of the British Association for the Adva of Sce showed that abouthalf of those present now embraced the idea of tial drift. (Hapgood soon after citedthis figure as proof of hically misled British geologists had bee.) Curiously,Holmes himself sometimes wavered in his vi. In 1953 he fessed: “I have neversucceeded in freeing myself from a nagging prejudice against tial drift; in mygeological bones, so to speak, I feel the hyp?hesis is a fantastie.”

    tial drift was irely without support in the Uates. Reginald Daly ofHarvard spoke for it, but he, you may recall, was the man who suggested that the Moon hadbeen formed by a ic impact, and his ideas teo be sidered iing, evenworthy, but a touch too exuberant for serious sideration. And so most Ameri academicsstuck to the belief that the tis had occupied their present positions forever and thattheir surface features could be attributed to something other than lateral motions.

    Iingly, oil pany geologists had known for years that if you wao find oil youhad to allow for precisely the sort of surfaents that were implied by plate teics.

    But oil geologists didn’t write academic papers; they just found oil.

    There was oher major problem with Earth theories that no one had resolved, or evene close to resolving. That was the question of where all the sediments went. Every yearEarth’s rivers carried massive volumes of eroded material—500 million tons of calcium, forinstao the seas. If you multiplied the rate of deposition by the number of years it hadbeen going on, it produced a disturbing figure: there should be about twelve miles ofsediments on the o bottoms—or, put another way, the o bottoms should by now bewell above the o tops. Stists dealt with this paradox in the ha possible way.

    They ig. But eventually there came a point when they could ig no longer.

    In the Sed World War, a Prion Uy mineralogist named Harry Hess utin charge of an attack transport ship, the USS Cape Johnson. Aboard this vessel was a fanew depth sounder called a fathometer, which was desigo facilitate inshore maneuversduring beach landings, but Hess realized that it could equally well be used for stificpurposes and never switched it off, even when far out at sea, even in the heat of battle. Whathe found was entirely ued. If the o floors were a, as everyone assumed, theyshould be thickly blaed with sediments, like the mud otom of a river or lake. ButHess’s readings showed that the o floor offered anything but the gooey smoothness ofa silts. It was scored everywhere with yons, trenches, and crevasses and dotted withvolic seamounts that he called guyots after an earlier Prion geologist named ArnoldGuyot. All this uzzle, but Hess had a war to take part in, and put such thoughts to theback of his mind.

    After the war, Hess returo Prion and the preoccupations of teag, but themysteries of the seafloor tio occupy a spa his thoughts. Meanwhile, throughoutthe 1950s oographers were uaking more and more sophisticated surveys of theo floors. In so doing, they found an even bigger surprise: the mightiest and mostextensive mountain range oh was—mostly—uer. It traced a tinuous pathalong the world’s seabeds, rather like the stitg on a baseball. If you began at Id, youcould follow it down the ter of the Atlantic O, around the bottom of Africa, and acrossthe Indian and Southern Os, below Australia; there it angled across the Pacific as ifmaking for Baja California before shooting up the west coast of the Uates to Alaska.

    Occasionally its higher peaks poked above the water as an island or archipelago—the Azoresand aries ilantic, Hawaii in the Pacific, for insta mostly it was burieduhousands of fathoms of salty sea, unknown and unsuspected. When all its brancheswere added together, the work exteo 46,600 miles.

    A very little of this had been known for some time. People laying o-floor cables in theeenth tury had realized that there was some kind of mountainous intrusion in the mid-Atlanti the way the cables ran, but the tinuous nature and overall scale of the was a stunning surprise. Moreover, it tained physical anomalies that couldn’t be explained.

    Down the middle of t..mid-Atlantic ridge was a yon—a rift—up to a dozen miles widefor its entire 12,000-mile length. This seemed to suggest that the Earth litting apart atthe seams, like a nut bursting out of its shell. It was an absurd and unnerving notion, but theevidence couldn’t be denied.

    Then in 1960 core samples showed that the o floor was quite young at the mid-Atlanticridge but grew progressively older as you moved away from it to the east or west. Harry Hesssidered the matter and realized that this could mean only ohing: new o crust wasbeing formed oher side of the tral rift, then being pushed away from it as new crustcame along behind. The Atlantic floor was effectively twe veyor belts, one carryingcrust toward North America, the other carrying crust toward Europe. The process becameknown as seafloor spreading.

    When the crust reached the end of its jour the boundary with tis, it plungedbato the Earth in a process known as subdu. That explained where all the sedime. It was beiuro the bowels of the Earth. It also explained why o floorseverywhere were so paratively youthful. None had ever been found to be older than about175 million years, which uzzle because tial rocks were often billions of yearsold. Now Hess could see why. O rocks lasted only as long as it took them to travel toshore. It was a beautiful theory that explained a great deal. Hess elaborated his ideas in animportant paper, which was almost universally ignored. Sometimes the world just isn’t readyfood idea.

    Meanwhile, two researchers, w indepely, were making some startling findingsby drawing on a curious fact of Earth history that had been discovered several decades earlier.

    In 1906, a French physicist named Bernard Brunhes had found that the pla’s magic fieldreverses itself from time to time, and that the record of these reversals is permaly fixed iain rocks at the time of their birth. Specifically, tiny grains of irohin the rockspoint to wherever the magic poles happen to be at the time of their formation, then staypointing in that dire as the rocks cool and harden. In effect they “remember” where themagic poles were at the time of their creation. For years this was little more than acuriosity, but in the 1950s Patrick Blackett of the Uy of London and S. K. Run ofthe Uy of Newcastle studied the a magic patterns frozen in British rocks andwere startled, to say the very least, to find them indig that at some time in the distant pastBritain had spun on its axis and traveled some distao the north, as if it had somehowe loose from its ms. Moreover, they also discovered that if you placed a map ofEurope’s magic patterns alongside an Ameri one from the same period, they fit togetheras ly as two halves of a torer. It was uny.

    Their findings were igoo.

    It finally fell to two men from Cambridge Uy, a geophysicist named DrummondMatthews and a graduate student of his named Fred Vio draw all the strands together. In1963, using magic studies of the Atlantic O floor, they demonstrated clusively thatthe seafloors were spreading in precisely the manner Hess had suggested and that thetis were in motion too. An unlucky adian geologist named Lawrence Morley cameup with the same clusion at the same time, but couldn’t find ao publish his paper.

    In what has bee a famous snub, the editor of the Journal of Geophysical Research toldhim: “Such speculations make iing talk at cocktail parties, but it is not the sort of thingthat ought to be published under serious stific aegis.” One geologist later described it as“probably the most signifit paper in the earth sces ever to be denied publication.”

    At all events, mobile crust was an idea whose time had finally e. A symposium ofmany of the most important figures in the field was vened in London uhe auspices ofthe Royal Society in 1964, and suddenly, it seemed, everyone was a vert. The Earth, themeeting agreed, was a mosaic of interected segments whose various stately jostlingsated for much of the pla’s surface behavior.

    The name “tial drift” was fairly swiftly discarded when it was realized that thewhole crust was in motion and not just the tis, but it took a while to settle on a namefor the individual segments. At first people called them “crustal blocks” or sometimes “pavingstones.” Not until late 1968, with the publication of an article by three Ameriseismologists in the Journal of Geophysical Research , did the segments receive the name bywhich they have since been known: plates. The same article called the new sce plateteics.

    Old ideas die hard, and not everyone rushed to embrace the exg heory. Well intothe 1970s, one of the most popular and iial geological textbooks, The Earth by thevenerable Harold Jeffreys, strenuously insisted that plate teics hysicalimpossibility, just as it had in the first edition way ba 1924. It was equally dismissive ofve and seafloor spreading. And in Basin and Range, published in 1980, John McPheehat even then one Ameri geologist i still didn’t believe in plate teics.

    Today we know that Earth’s surface is made up of eight to twelve big plates (depending onhow you define big) and twenty or so smaller ones, and they all move in different diresand at different speeds. Some plates are large and paratively inactive, others small buteic. They bear only an ial relationship to the landmasses that sit upoheNorth Ameri plate, for instance, is much larger than the ti with which it isassociated. It roughly traces the outline of the ti’s western coast (which is why thatarea is so seismically active, because of the bump and crush of the plate boundary), butighe eastern seaboard altogether and instead extends halfway across the Atlantic to themid-o ridge. Id is split down the middle, which makes it teically half Amerid half European. New Zealand, meanwhile, is part of the immense Indian O plate eventhough it is nowhere he Indian O. And so it goes for most plates.

    The es between modern landmasses and those of the past were found to beinfinitely more plex than anyone had imagined. Kazakhstan, it turns out, was oached to Norway and New England. One er of Staten Island, but only a er, isEuropean. So is part of Newfoundland. Pick up a pebble from a Massachusetts beach, and its kin will now be in Africa. The Scottish Highlands and much of Sdinavia aresubstantially Ameri. Some of the Shacklete of Antarctica, it is thought, may oncehave beloo the Appalas of the eastern U.S. Rocks, in shet around.

    The stant turmoil keeps the plates from fusing into a single immobile plate. Assumingthings tinue much as at present, the Atlantic O will expand until eventually it is muchbigger than the Pacific. Much of California will float off and bee a kind of Madagascar ofthe Pacific. Africa will push northward into Europe, squeezing the Mediterranean out ofexistend thrusting up a  of mountains of Himalayan majesty running from Paris toCalcutta. Australia will ize the islands to its north and ect by some isthmianumbilicus to Asia. These are future outes, but not future events. The events are happeningnow. As we sit here, tis are adrift, like leaves on a pond. Thanks to Global PositioningSystems we  see that Europe and North America are parting <samp></samp>at about the speed a fingernailgrhly two yards in a human lifetime. If you were prepared to wait long enough,you could ride from Los Angeles all the  to San Francisco. It is only the brevity oflifetimes that keeps us from appreciating the ges. Look at a globe and what you areseeing really is a snapshot of the tis as they have been for just oh of 1 pertof the Earth’s history.

    Earth is alone among the rocky plas in havionics, and why this should be is a bitof a mystery. It is not simply a matter of size or density—Venus is nearly a twin of Earth inthese respects a has onic activity. It is thought—though it is really nothing morethan a thought—that teics is an important part of the pla’s anic well-being. As thephysicist and writer James Trefil has put it, “It would be hard to believe that the tinuousmovement of teic plates has no effe the development of life oh.” He suggeststhat the challenges induced by teics—ges in climate, for instance—were animportant spur to the development of intelligehers believe the driftings of thetis may have produced at least some of the Earth’s various extin events. InNovember of 2002, Tony Di of Cambridge Uy in England produced a report,published in the journal Sce, strongly suggesting that there may well be a relationshipbetween the history of rocks and the history of life. What Di established was that thechemical position of the world’s os has altered abruptly and vigorously throughoutthe past half billion years and that these ges often correlate with importas inbiological history—the huge outburst of tiny anisms that created the chalk cliffs ofEngland’s south coast, the sudden fashion for shells among marine anisms during theCambrian period, and so on. No one  say what causes the os’ chemistry to ge sodramatically from time to time, but the opening and shutting of o ridges would be anobvious possible culprit.

    At all events, plate teiot only explaihe surface dynamics of the Earth—how ana Hipparion got from Frao Florida, for example—but also many of its internalas. Earthquakes, the formation of island s, the carbon cycle, the locations ofmountains, the ing of ice ages, the ins of life itself—there was hardly a matter thatwasn’t directly influenced by this remarkable heeologists, as McPhee has noted,found themselves in the giddying position that “the whole earth suddenly made sense.”

    But only up to a point. The distribution of tis in former times is much less lyresolved than most people outside geophysics think. Although textbooks give fident-looking representations of a landmasses with names like Laurasia, Gondwana, Rodinia,and Pahese are sometimes based on clusions that don’t altogether hold up. AsGeaylord Simpson observes in Fossils and the History of Life, species of plants andanimals from the a world have a habit of appearing invely where they shouldn’tand failing to be where they ought.

    The outline of Gondwana, a once-mighty ti eg Australia, Afritarctica, and South America, was bas<s></s>ed in large part on the distribution of a genus ofaongue fern called Glossopteris, which was found in all the right places. However,much later Glossopteris was also discovered in parts of the world that had no knowne to Gondwana. This troubling discrepancy was—and tio be—mostlyignored. Similarly a Triassic reptile called Lystrosaurus has been found from Antarctica allthe way to Asia, supp the idea of a former e between those tis, but ithas urned up in South America or Australia, which are believed to have been part ofthe same ti at the same time.

    There are also many surface features that teics ’t explain. Take Denver. It is, aseveryone knows, a mile high, but that rise is paratively ret. When dinosaurs roamedthe Earth, Denver art of an o bottom, many thousands of feet lower. Yet the ro which Denver sits are not fractured or deformed in the way they would be if Denver hadbeen pushed up by colliding plates, and anyway Denver was too far from the plate edges to besusceptible to their as. It would be as if you pushed against the edge of a rug hoping toraise a ruck at the opposite end. Mysteriously and over millions of years, it appears thatDenver has been rising, like baking bread. So, too, has much of southern Africa; a portion ofit a thousand miles across has risen nearly a mile in 100 million years without any knownassociated teic activity. Australia, meanwhile, has been tilting and sinking. Over the past100 million years as it has drifted north toward Asia, its leading edge has sunk by some sixhundred feet. It appears that Indonesia is very slowly drowning, and dragging Australia downwith it. Nothing iheories of teics  explain any of this.

    Alfred Wegener never lived to see his ideas vindicated. On an expedition to Greenland in1930, he set out alone, on his fiftieth birthday, to check out a supply drop. He never returned.

    He was found a few days later, frozen to death on the ice. He was buried on the spot and liesthere yet, but about a yard closer to North America than on the day he died.

    Einstein also failed to live long enough to see that he had backed the wrong horse. In fact,he died at Prion, New Jersey, in 1955 before Charles Hapgood’s rubbishing of tialdrift theories was even published.

    The other principal player in the emergence of teics theory, Harry Hess, was also atPrion at the time, and would spend the rest of his career there. One of his students was abright young fellow named Walter Alvarez, who would eventually ge the world ofs a quite different way.

    As feology itself, its cataclysms had only just begun, and it was young Alvarez whohelped to start the process.

    PART IV  DANGEROUS PLAhe history of any one part of theEarth, like the life of a soldier, sistsof long periods of boredom andshort periods of terror.

    -British geologist Derek V. Ager

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