Chapter 14 Chapter 12 The Earth Is Moving

In 1955, Albert Einstein did his last professional job—writing a short but vivid foreword to a book.The title of the book is "The Moving Crust: Answering Some Questions in Earth Science" by a geologist named Charles Hapgood.In his book, Hapgood firmly refuted the notion that continents were drifting.In a tone that made everyone laugh with him, he pointed out that the gullible few thought that "there are some continents that obviously fit together." .He went on to say that it seemed that "South America could be put together with Africa, and so on, and it was even claimed that the rock formations on both sides of the Atlantic were identical".

Mr. Hapgood categorically rejects any such notion, and points out that the geologists KE Custer and JC Mendes have carried out extensive fieldwork on both sides of the Atlantic to establish beyond doubt that these similarities are at all does not exist.God knows where Messrs. Castor and Mendez inspected, for many of the rock formations on both sides of the Atlantic are indeed the same--not only very similar, but exactly the same. Neither Mr. Hapgood nor many other geologists of the day could take this view to heart. The theory mentioned by Hapgood was first proposed in 1908 by an American amateur geologist named Frank Bursley Taylor.Taylor was born into a wealthy family with sufficient financial means and freedom from academic constraints to pursue research in unusual ways.He suddenly discovered that the shape of the African coast is very similar to that of the opposite South American coast.Based on this observation, he proposed the idea that the continents once slid around.He proposed--provided presciently, it turned out--that several continents crashed together to form the world's mountains.However, he produced little evidence, and the theory was deemed unrealistic to be taken seriously.

In Germany, however, there was a theorist who accepted Taylor's views and took them very seriously.He is Alfred Wegener, a meteorologist at the University of Marburg.Wegener examined many plant and fossil anomalies that did not fit into standard models of Earth's history.He realized that it simply didn't make sense to explain it in conventional ways.Animal fossils keep appearing on both sides of the ocean, and the ocean is so wide that animals obviously cannot swim across it.He wondered, how did marsupials get from South America to Australia?Why do the same snails appear in Scandinavia and New England?How do you explain that coal seams and other subtropical remnants are present in colder regions like Spitsbergen if they hadn't somehow migrated from hotter climates?

Wegener proposed a theory that the world's continents originally belonged to a single landmass, which he called "Pangaea", and that flora and fauna could be mixed together; only later did the combined ancient land break up into several pieces , drifting to the current position.He wrote "The Origin of Land and Sea" to illustrate his views. It was published in German in 1912 - despite the outbreak of World War I two years later - and in English three years later. Because of the war, Wegener's theory did not attract much attention at first.However, he published a revised and expanded version in 1920, and it soon became a topic of discussion.Everyone agrees that the continents are moving -- not side to side, but up and down.The process of vertical movement, known as isostasis, has been the basis of generations of geological beliefs, although no one has come up with a convincing theory of how or why it happens.One insight that was still in textbooks when I was in elementary school was the "dried cloudberry" theory put forward by the Austrian Eduard Hughes at the turn of the century.The theory is that as the scorching Earth cooled, it shrunk into the shape of dried cloudberries, creating oceans and mountains.

Not to mention that James Hutton had long ago said: Had such a static arrangement been made, the earth would have been a featureless sphere as erosion had flattened the convexities and filled in the concaves.Rutherford and Soddy also pointed out another problem in the early 20th century: the Earth harbors a huge amount of heat—too big to even mention the cooling and shrinking that Huwees talked about.In any case, if Hughes' theory were true, the mountains would be spread evenly across the Earth's surface, which is clearly not the case; the ages would be about the same, and by the early 20th century it was clear , some mountain ranges (such as the Urals and Appalachians) are hundreds of millions of years older than others (such as the Alps and Rocky Mountains).The time was clearly ripe for a new theory.Unfortunately, geologists did not wish to entrust this task to Alfred Wegener.

First, his views were radical, questioning the foundations of their discipline and unlikely to generate much enthusiasm among his audience.Such a challenge would have been painful even from a geologist, and Wegener had no background in geology.God, he's a meteorologist, a weatherman -- a German weatherman.This defect is irreparable. So geologists go out of their way to refute his evidence and belittle his insights.In order to avoid the problem of fossil distribution, they built ancient "land bridges" as long as they were needed there.A land bridge was built across the Atlantic Ocean when it was discovered that an ancient horse called the "Three-toed Horse" lived in both France and Florida, USA.When they discovered that ancient tapirs existed in both South America and Southeast Asia, they built another land bridge.Before long, maps of the prehistoric oceans were almost full of hypothetical land bridges—from North America to Europe, from Brazil to Africa, from Southeast Asia to Australia, and from Australia to Antarctica.The curly joins appear quickly, as often as needed, to move a creature from one continent to another, and disappear quickly, before disappearing without a trace.Of course, there is not the slightest basis for such a thing - it is completely wrong.

However, it was the orthodoxy in geology for half a century thereafter. There are things that even land bridges cannot explain.A species of trilobite known in Europe was found to have lived in Newfoundland - but only on one side of the island.No one can convincingly explain how the trilobites can cross the turbulent sea of ​​3000 kilometers, but they can't get around the 300 kilometers wide island corner.Another species of trilobite was even more anomalous, showing up in Europe and the Pacific coast of the northwestern United States, but not in the middle.This requires a flyover rather than a land bridge.However, until 1964, when discussing various theories, Encyclopedia Britannica described Wegener's theory as "ridden with many serious theoretical problems".It is true that Wegener made mistakes.His assertion that Greenland is drifting westward at a rate of about 1.6 kilometers per year is total nonsense. (1 cm is more likely.) In particular, he cannot provide a convincing explanation for continental movement.To believe his theory, you have to admit that the continents were somehow pushed through the solid crust like a plow, without leaving furrows behind.Based on what was known at the time, it was impossible to explain what force drove such a large-scale movement.

British geologist Arthur Holmes has made a great contribution to determining the age of the earth.This time it was he who made a point.Holmes was the first scientist to know that radiant heat convects the Earth's interior.Theoretically, this convection could be so powerful that it could make the continental plane slide. In 1944, Holmes first published a popular and influential textbook, Principles of Physical Geology.In this book, he proposed the theory of continental drift.Many of the basic principles of the theory still prevail today.It was still a radical view at the time and was criticized by many, especially in the United States.Americans have resisted the drift doctrine longer than elsewhere.An American commentator worried that Holmes' argument was clear and convincing, and students would gradually believe it.There was no sarcasm in his words.Elsewhere, however, the new theory has received firm, if cautious, support. In 1950, a vote at the annual meeting of the British Association for the Advancement of Science showed that about half of the delegates had now embraced the idea of ​​continental drift. (After a while, Hapgood cites this figure as evidence of how woefully misguided British geologists have been.) Interestingly, Holmes himself sometimes wavered a bit about himself. In 1953, he admitted: "I have never been able to shake off a disturbing aversion to the theory of continental drift; in my bones as a geologist, IMHO, I find the hypothesis to be an absurd one."

The theory of continental drift is not completely unsupported in the United States.Reginald Daly of Harvard University defended it.But, as you may recall, he was the gentleman who proposed that the moon was formed by a cosmic impact.People tend to think that his views are meaningful, even valuable, but a bit flashy and therefore not worthy of serious consideration.Consequently, most American scholars insist that the continents have always been where they are now, and that their superficial features can be attributed to causes other than lateral movement. Interestingly, oil company geologists have known for years that to find oil you have to account for exactly this surface movement that plate tectonics necessarily entails.However, petroleum geologists do not write academic papers.They only look for oil.

There is another problem in earth theory that no one has solved, or has come close to solving.That is, where did all this sediment go?Earth's rivers carry vast amounts of eroded material -- for example, 500 million tons of calcium -- into the sea each year.If you multiply the number of years of this process by the rate of deposition, you get a staggering number: there should be a layer of sediment on the seafloor about 20 kilometers thick -- or to put it another way, the seafloor should now be well above the surface .Scientists deal with this unthinkable problem in the simplest possible way -- by leaving it alone.But, finally, a moment has come when ignoring it is no longer enough.

During World War II, Princeton University mineralogist Harry Hess commanded an attack transport ship, the USS Pointe Johnson.The ship was equipped with an advanced new depth sounder called an echo sounder for easier operation during beach landings.However, Hess realized that the instrument could also be used for scientific purposes, so he never turned it off, even at high seas, even in the heat of battle.What he found was completely unexpected.If the bottom of the sea is as old as it is supposed to be, there should be a thick layer of sediment, like the silt on the bottom of a river or lake.However, Hess' measurements show that the sea floor is just a slimy, smooth layer of ancient sediment.It is full of cliffs, ravines and fissures, and dotted with undersea volcanoes, or mesa.He called it Guyot, in honor of the early Princeton geologist Arnold Guyot.It was all a mystery, but Hess' mission was to fight wars, and he put those thoughts to the back of his mind. When the war was over, Hess returned to Princeton to teach mainly, but the mysteries of the sea still had a place in his mind.Meanwhile, throughout the 1950s, oceanographers probed deeper and deeper into the seafloor.In the process, they discover something even more unexpected: The most majestic and largest mountain range on Earth is — mostly — underwater.It stretches along the ocean floor of the world like the pattern on a tennis ball.If you start heading south from Iceland, you can follow this mountain range to reach the center of the Atlantic Ocean, then go around the bottom of Africa, cross the Indian Ocean and the South Pacific Ocean, and enter the Pacific Ocean below Australia; then, it crosses the Pacific Ocean diagonally, as if going to the California peninsula , actually bulges suddenly, becoming the west coast of the continental United States to Alaska.Occasionally, its peaks poke out of the water to form islands or archipelagos—the Azores and Canary Islands in the Atlantic, for example, and the Hawaiian Islands in the Pacific, for example—but most are submerged several kilometers below the surface, uninhabited. Know, no one thought.If all the branches are added together, the total length of the mountain range is 75,000 kilometers. For a while, very little was known about these. Those who laid submarine cables in the 19th century had discovered that there were mountains in the mid-Atlantic blocking the course of the cables, but the coherent nature and overall extent of the mountains were completely unexpected.Also, its shape is so irregular that it is difficult to explain.In the middle of that hill in the mid-Atlantic, there is a canyon below—a chasm—20 kilometers wide and 19,000 kilometers long.This seems to indicate that the Earth is splitting in half along a crack, like a nut popping out of its shell.The idea is grotesque and disturbing, but the signs are undeniable. Then, in 1960, core samples showed that the ridges of the mid-Atlantic seafloor were quite young, but getting older from east to west.After thinking about it, Harry Hess thinks that there is only one meaning for that situation: new seafloor crust is forming on both sides of the central crack, and then pushed outward by the newer crust that is produced later.The floor of the Atlantic Ocean is actually two large conveyor belts, one carrying the crust to North America and the other to Europe.This process came to be known as seafloor spreading. After the crust reaches the end point at the junction with the continent, it suddenly turns back into the interior of the earth. This process is called subduction.The theory explains where so much sediment went.It turned out that it returned to the belly of the earth continuously.The theory also explains why the seafloor there is relatively young.It was found that the age of the sea floor there is no more than 175 million years.This is a mystery because rocks on continents tend to be billions of years old.Now, Hess finally understood that the existence time of the rock on the seabed is only the time it takes to reach the sea.It's a beautiful theory that explains a lot of things.Hess laid out his views in an important paper.However, these views have received little widespread attention.Sometimes the world is really unprepared for good insights. Meanwhile, two researchers working independently are getting some surprising results using an interesting fact about Earth's history that was discovered decades ago. In 1906, French physicist Bernard Bruna discovered that the planet's magnetic field reversed itself from time to time, and that the reversals were permanently recorded in certain rocks that were forming.Specifically, small particles of iron ore in rocks point toward the magnetic poles, wherever they happen to be when they form, and then point in that direction forever as the rock cools and solidifies.In effect, the rock "remembers" the orientation of the magnetic poles when it was formed.For years, people just thought it was funny.But in the 1950s, Patrick Blackett of the University of London and SK Runcorn of the University of Newcastle studied ancient magnetic field patterns solidified in British rocks, and were quite surprised to find, to say the least, that those rocks showed that in the distant At some point in the past, Britain rotated on its axis and moved some distance to the north, as if it had somehow escaped the cable.And, they found, if you put a map of the magnetic field pattern of Europe next to a map of the American magnetic field pattern from the same period, the two fit together perfectly, like a letter that has been torn in half.It's a little weird.Their findings also went unnoticed. In the end, it was two men at the University of Cambridge who pulled the threads together.One was the geologist Drummond Matthews, and the other was one of his graduate students named Fred Vine.Using their studies of the magnetic field of the Atlantic seabed, they convincingly showed that the seabed was expanding in the manner Hess speculated, and that the continents were also shifting.The unlucky Canadian geologist Lawrence Morey came to the same conclusion at the same time but couldn't find anyone to publish his paper. The editor of the "Journal of Geophysical Research" told him: "These speculations are interesting for cocktail party chat materials, but they should not be published in a serious scientific journal." The incident became a snub Famous example of others.One geologist later described it as "quite possibly the most significant earth science paper ever rejected for publication". In any case, the time has finally come to raise the idea of ​​a shifting crust. In 1964, many of the most important figures in the field attended a symposium hosted by the Royal Society in London.Suddenly, it seemed like everyone had changed their minds.The meeting agreed that the Earth is a mosaic of interconnected fragments.Their jostling and jostling explains many phenomena on the Earth's surface. It wasn't long before the name "continental drift" was dropped as it was realized that it wasn't just the continents that were moving, but the entire Earth's crust.However, it took some time before a name was settled on for those fragments.At first, people called them "crustal building blocks", and sometimes "paving stones".It wasn't until late 1968, when three American seismologists published a paper in the Journal of Geophysical Research, that the fragments got their current name: Plates.The same article calls this new disruption "plate tectonics." Old ideas die hard, and not everyone is quick to embrace exciting new theories.Until the 1970s, a popular and influential textbook on geology by the venerable Harold Jeffries insisted, as it did in its first edition in 1924, that the theory of plate tectonics was physically cannot be established.It also disregards the theory of convection and seabed expansion.In Seas and Mountains, published in 1980, John McPhee pointed out that even then, 1 in 8 American geologists did not believe in plate tectonics. Today, we know that the Earth's surface is made up of 8-12 large plates (depending on how you define size); they are all moving at different speeds and in different directions.Some plates are very large and not very active; some are small but have great energy.They have only one incidental relationship to the landmass they are on.For example, the North American plate is much larger than its associated continents.It stretches roughly along the west coast of the continent (an area where earthquakes often occur due to bumps in the plate boundaries), but has absolutely no relation to the east coast, and instead crosses the Atlantic halfway to the mid-Atlantic ridge.Iceland is divided in two from the middle, on the plate, half belongs to America and half belongs to Europe.At the same time, New Zealand is part of the huge Indian Ocean plate, although the country is far from the Indian Ocean.This is the case for most plates. It has been discovered that the relationship between modern land blocks and ancient land blocks is much more complicated than imagined.Kazakhstan was once connected to Norway and New England.A corner of Staten Island, just a corner, belongs to Europe.Parts of Newfoundland too.Pick up a rock on a beach in Massachusetts, and you'll find its closest relatives in Africa today.Much of the Scottish Highlands and Scandinavia belong to America.It is thought that parts of Antarctica's Shackleton Range may have once belonged to the Appalachian Mountains in the eastern United States.In short, rocks come and go. Due to continuous turbulence, these plates do not merge into one stationary plate.If things continue roughly as they are now, the Atlantic Ocean will eventually be much larger than the Pacific Ocean.A large part of California will drift off the mainland, becoming the Madagascar of the Pacific Ocean.Africa would push north toward Europe, pushing the Mediterranean out of the way and raising a majestic Himalaya between Paris and Calcutta.Austria will be connected to the islands to the north, facing Asia across a long and narrow isthmus.These are future results, not future events.Things are happening now.As we sit here, the continent is drifting like a leaf in a pond.Thanks to GPS, we can see that Europe and North America are drifting apart at the rate that fingernails grow -- about two meters in a human lifetime.You can ride from Los Angeles all the way to San Francisco if you're willing to wait a long time.It is only because human life is too short that we cannot enjoy this change.If you look at a globe, what you see is really just a snapshot of the state of the continents during one-thousandth of the Earth's history. Among rocky planets, only Earth has plates.Why this is so is somewhat of a mystery.It's not just a matter of size or density -- in these respects Venus is pretty much Earth's twin, but it doesn't have plate activity.It is thought--really just thought--that the plates are an important part of the Earth's organism.As physicist and author James Trefil puts it: "It is inconceivable that the shifting of tectonic plates had no effect on the development of life on Earth." He argues that challenges raised by structural geology -- such as climate Change - an important catalyst for the advancement of knowledge.It has also been suggested that continental drift is responsible for at least some of the extinctions on Earth. In November 2002, Tony Dixon of the University of Cambridge wrote a report in the journal Science strongly arguing that the history of rocks and the history of life may be linked.Dixon confirmed that over the past five billion years, the chemical structure of the world's oceans has changed often suddenly and dramatically; these changes are often associated with major events in biological history - such as the sudden appearance of the hordes of microorganisms that later formed the southern coast of England the chalky cliffs of the 1990s; the sudden increase in Cambrian shellfish in marine life; and so on.No one can tell what caused the dramatic changes in ocean chemistry from time to time.But the opening and closing of the ridges clearly could be the reason. In any case, plate tectonics explains not only the Earth's surface dynamics -- how, for example, an ancient three-toed horse ran from France to Florida -- but also much of its interior.Earthquakes, the formation of archipelagoes, the carbon cycle, the position of mountain ranges, the onset of ice ages, the origin of life itself -- hardly a single thing was not directly influenced by this marvelous new theory.Geologists were dazzled, McPhee said, and "suddenly the whole planet made sense." But, only to a certain extent.The distribution of continents in past ages is not as well resolved as most non-geophysicists believe.Although the textbooks seem to list the ancient continents with confidence, such as Laura, Gondwana, Rodinia, and Pangea, sometimes they are not completely established. based on the conclusions.In Fossils and the History of Life, George Gaylord Simpson pointed out that many species of plants and animals of the ancient world were where they shouldn't be and where they weren't. Gondwana was once a large landmass connecting Australia, Africa, Antarctica and South America.Its territory is largely determined by the distribution of an ancient species of linguosa fern called Shiwei.Stone reeds are found where they should be found.Much later, however, Glossula ferns were also found in other parts of the world that were not connected to Gondwana.For the most part, this troubling contradiction was — and still is — largely ignored.Likewise, a Triassic reptile called Watersaurus has been found from Antarctica to Asia, but the two places are thought to have belonged to the same continent at about the same time. There are also many ground features that structural geology cannot explain.Take Denver, Colorado, for example.As you all know, this place is 1,500 meters above sea level, but that height is only a recent occurrence.When dinosaurs roamed the earth, Denver was part of the ocean floor, thousands of meters below the surface.However, the rock beneath Denver has not worn down and has not deformed.That shouldn't be the case if Denver is held up by colliding plates.In any case, Denver is too far from the edges of the plates to be affected by them.It's as if you were pushing against the edge of a rug, hoping to create a pleat at the opposite end.For millions of years, Denver seems to have been mysteriously rising like bread.The same is true of many parts of southern Africa.One of these is a 1,600-kilometer-wide patch that has uplifted about 1.5 kilometers over 10 million years without any known tectonic activity.At the same time, Australia is gradually tilting and sinking.in the past 1 Over 100 million years, it drifted north towards Asia on the one hand, and its main edge sank by nearly 200 meters on the other.It appears that Indonesia is slowly submerging, dragging Australia down with it.Structural theory cannot explain these phenomena at all. Alfred Wegener did not live long enough to see his ideas proven correct. In 1930, on his 50th birthday, he set off on a solo expedition to Greenland to check for air-dropped supplies.He never came back.A few days later, he was found frozen to death on the ice.He was buried there, and is still there today, only about 1 meter closer to North America than the day he died. Nor did Einstein live to see himself on the wrong side.He died in Princeton, New Jersey in 1955, actually before Charles Hapgood published his "nonsense" theory of continental drift. Harry Hess, another major figure in the theory of tectonics, was also at Princeton at the time, where he would spend the rest of his life.One of his students was a brilliant young man named Walter Alvarez, who would end up changing the world of science in quite a different way. As for geology itself, the revolution was just beginning, and the young Alvarez was instrumental in kickstarting the process. [ END ]