explain why magnetic striping on the seafloor is evidence for plate movement.?
85089
Imagine that you had a big globe filled with Play-Dough and that this globe had cracks in it through which you suspected that Play-Dough was regularly squished from the inside of the globe onto the surface of the globe.  You know that all of the Play-Dough on the inside of the globe spontaneously changes from red to blue at somewhat regular intervals.  Now, you notice that on the outside of the globe, around the cracks, there are stripes of play-dough running parallel to the cracks in the globe...a red strip, and then a blue strip, and then a red strip, and then a blue strip...\n\nYou could reasonably surmise that the alternating red and blue stripes were created as Play-Dough from the inside of the globe was slowly, over a long period of time, squished out onto the surface of the globe, and the stripes originate as the Play-Dough on the inside of the globe suddenly changes from red to blue and back again.  As the Play-Dough is slowly squished out, it moves the Play-Dough that was squished out before it further from the crack, so the alternating stripes of Play-Dough (the plates of the earth) are slowly moving across the surface of the globe.\n\nThe red and blue Play-Dough represents the alternating magnetism of the earth...red is, say, when North points to what we now call North, and blue, the alternate color, is when the earth's magnetism flips and and North is South.  (During one of these periods a compass on earth would point South rather than North.)\n\nHope this helps
841947
A mid ocean ridge is an area where new sea floor is created throught the divergent (speading) motion of the tectonmic plates in that area. At mid ocean ridges, fractures from the pulling allow small amounts of magma to squeeze in and push the plates that much more.\n\nIt comes down to density. The center of the ridge is high, because it it new (just formed) and hot. The edges are low because it is old and cold. There are two main theories on the cause: slab pull and ridge push.\n\nRidge push is the classic idea that the ridge is a high point of a convection current, pushing the plates aside and allowing new mantle material to rise up and fill the hole.\n\nSlab pull is the new idea that the subducting end of the plate, that is really old and dense, pulls on the entire plate as it subducts, and thus pulls apart itself in places, causing a hole which is then filled by rising material, forming the ridge.\n\nIt's kinda a chicken/egg thing, so we may never be able to rule one or the other out.
164797
this is a vague queston. But I believe i know what you are asking. Well He already believed that Pangea had formed and broken apart. Evidence from Glacial Striations and rock formations, not to mension an almost perfect mactch of shorelines. I guess it would have more support for his theory. He concluded that the continents were moving. What he could not prove was the mechinism for the movement. it is not actually the continents moving. They are hitching a ride on the techtonic plates.
166771
You have confused 2 different techniques I suspect. \n\nMagnetotelluric methods use EM fields to probe the interior of the earth. Seismic methods use mechanical waves, a different technique.
377429
It is a divergent plate boundary found running down the middle of the Atlantic Ocean. Hence the name "Mid Atlantic Ridge".\n\nThis is where two lithospheric plates are moving apart from each other.\n\nWhere they spread apart, new continental crust is being created. It is said that the US & the UK move about 1 - 2 inches apart every year. The US is getting further from Europe all the time!
24692
The best answer from the above choices: \nSlow moving convection currents within the molten aesthenosphere supply new material to the spreading centers in the earth's ocean floors and other places. These currents are thought to provide force to cause the motion of the oceanic plates, either directly, or indirectly through the mid ocean ridge building process. \n\nSubduction is only one part of the process of plate tectonics, that does provide some driving force by pulling the subducting plate downward. \n\nGravity has a role as well, as without gravity, the mid-ocean ridges would not have the weight to provide force with which to push the plates apart at the spreading centers, and the subducting plates would not have the force to pull plates. \n\nThe earth's magnetic field may have the least to do with plate tectonics, possibly no role at all.
374996
My favourite is the test done to prove the magnetic force of earth.  I do not remember who the scientist was but in the dome of St. Pauls's Cathedral in London UK, he suspended a rope from the highest point down to the ground where he had a level patch of sand.  A weighted point on the rope was just about able to touch the sand.  Sure enough, as time went on the rope began to move with the direction of the earth leaving evidence of stripes in the sand.
933188
The idea of Continental Drift was the forerunner of Plate Tectonics Theory. At the time that Wegener proposed the idea of Continental Drift, he did not have sufficient information to explain the physical mechanisms that would have allowed continents to break apart and drift apart. He did have fossil evidence, and shape-of-the continents evidence, and matching-rocks-on-both-sides evidence that the continents had indeed been juxtaposed. "A fatal weakness in Wegener's theory was that it could not satisfactorily answer the most fundamental question raised by his critics: What kind of forces could be strong enough to move such large masses of solid rock over such great distances? Wegener suggested that the continents simply plowed through the ocean floor, but Harold Jeffreys, a noted English geophysicist, argued correctly that it was physically impossible for a large mass of solid rock to plow through the ocean floor without breaking up."http://pubs.usgs.gov/gip/dynamic/historical.html\n\nLater, when scientists discovered magnetic striped on the ocean floor, learned more about the seismicity at trenches, and so forth, they were able to put together a more comprehensive model of the actual physical processes that could and do cause the continents to "drift" apart, or collide together. These processes come under the heading of Plate Tectonics--which includes the ideas of three types of plate boundaries, including the divergent boundaries with spreading ridges required for continents to "drift" apart. \nThe website below will give you illustrations and discusses both continental drift and plate tectonics.
58110
It is quite simple really. There is no 'theory' as some of the posts have indicated. The earth is composed of a number of large plates, which move constantly (the Pacific Ocean today is spreading at 4-5 cm per year). As these plates move, they sometimes slide under one another. As this happens, the upper plate is lifted. This moves rock that was deposited in an ocean environment slowly upwards and often to the top of mountains. The process takes millions of years, so it is likely the rocks that contain the shells on the top of the mountain your husband refers to are tens of millions of years old, or older. \n\nA perfect example is Mount Everest, which has carbonate rocks (with shells) at the peak. Other examples are many parts of the Rocky Mountains in North America, and the Alps in Europe. The Sierra's in California also contain carbonate rocks in many places that did in fact originate in what is now the Pacific Ocean. It is not rare and not mysterious or theoretical. \n\nThe names of these processes, in case you want to learn more, are plate tectonics (previously called continental drift), subduction (one plate under another), orogeny (mountain building), and carbonate sedimentology( deposition of carbonate rocks).  I'm including some links with basic explanation of the concepts. \n\nAnimated illustrations of plate tectonics:\nhttp://www.ucmp.berkeley.edu/geology/tectonics.html\n\nIllustration of subduction:\nhttp://www.platetectonics.com/book/page_12.asp\n\nOrogeny:\nhttp://www.uwgb.edu/dutchs/platetec/orogeny.htm\n\nCarbonate sedimentology (great pictures of carbonates in mountains (sea shells):http://epswww.unm.edu/sed/home.htm\nOther carbonate sedimentology links:\nhttp://www.unige.ch/sciences/terre/geologie/w_groups/carbonate_sedimentology/webmain.html\n\nIf you want to see my explanation for how sea shells form in the ocean go to this question:\nhttp://answers.yahoo.com/question/index;_ylt=AiyMjODIRNiCqQ3uGA0_ICPsy6IX?qid=1006011004317
809527
I think its called 'subduction', where one tectonic plate goes under another. It occurs at 'subduction zones', such as on the west coast of the United States. The reason it occurs is that one plate is expanding and the edges need to go somewhere (under another plate). For example, the Atlantic plate is expanding from the center because there is a north-to-south line of underwater volcanoes, spewing out magma and forcing the 2 halves of the plate apart to the west and east.
327692
because there is a subduction zone. One plate goes under the other and melts into the earth's mantle.
133507
The magnetic striping of the seafloor is similiar on both sides of an oceanic rift.  They match up like puzzle pieces.
536734
Alfred Wegener, German meteorologist, was gathering climate information with a partner when he started noticing glacial deposits that matched on different continents.\n\nThis led to more study of course. Why were similar deposits found in such far removed places?\n\nWhile looking into this, he also noticed that rocks & fossils on different continents were also identical.\n\nThis, along w/ the "continent puzzle" led to his hypothesis of continental drift. Notice, it is referred to as a hypothesis. This is because Wegener could never provide a driving mechanism for continental drift.\n\nWegener tried explaining how continents could move but to no avail. His explanation that the continental crust literally plowed through oceanic crust did not "cut" it. PUN intended. This was not possible w/o leaving torn crustal plates behind & there was no evidence of that.\n\nMost scientists rejected his hypothesis. Some, however, kept searching for the "driving mechanism" behind continental drift.\n\nIn 1968, scientists could finally provide this force behind the movement of the crust. It was named the theory of plate tectonics.\n\nThis theory stated that the earth's crust was broken down into many major & minor lithospheric plates. These plates moved due to uneven heating of the molten magma in the earth's mantle.\n\nConvection currents w/in the mantle are created by cooler magma sinking & hotter magma rising. As the hotter magma rises towards the asthenosphere, it will cool & then sink. This principle works in the same manner as it does in the atmosphere.\n\nPlates were either pulled apart at divergent boundaries or subducted at convergent boundaries unless it is at two continental convergent boundaries. In this case the two crusts are less dense than the magma below & will deform rather than be subducted.\n\nSo yes, Alfred Wegener did suggest the theory of continental drift. But it was not actually taken seriously until the theory of plate tectonics came along.
894274
The idea of Continental Drift was the forerunner of Plate Tectonics Theory. At the time that Wegener proposed the idea of Continental Drift, he did not have sufficient information to explain the physical mechanisms that would have allowed continents to break apart and drift apart. He did have fossil evidence, and shape-of-the continents evidence, and matching-rocks-on-both-sides evidence that the continents had indeed been juxtaposed. "A fatal weakness in Wegener's theory was that it could not satisfactorily answer the most fundamental question raised by his critics: What kind of forces could be strong enough to move such large masses of solid rock over such great distances? Wegener suggested that the continents simply plowed through the ocean floor, but Harold Jeffreys, a noted English geophysicist, argued correctly that it was physically impossible for a large mass of solid rock to plow through the ocean floor without breaking up."http://pubs.usgs.gov/gip/dynamic/historical.html\n\nLater, when scientists discovered magnetic striped on the ocean floor, learned more about the seismicity at trenches, and so forth, they were able to put together a more comprehensive model of the actual physical processes that could and do cause the continents to "drift" apart, or collide together. These processes come under the heading of Plate Tectonics--which includes the ideas of three types of plate boundaries, including the divergent boundaries with spreading ridges required for continents to "drift" apart. \n\n"From seismic and other geophysical evidence and laboratory experiments, scientists generally agree with Harry Hess' theory that the plate-driving force is the slow movement of hot, softened mantle that lies below the rigid plates. This idea was first considered in the 1930s by Arthur Holmes, the English geologist who later influenced Harry Hess' thinking about seafloor spreading. Holmes speculated that the circular motion of the mantle carried the continents along in much the same way as a conveyor belt. However, at the time that Wegener proposed his theory of continental drift, most scientists still believed the Earth was a solid, motionless body. We now know better. As J. Tuzo Wilson eloquently stated in 1968, "The earth, instead of appearing as an inert statue, is a living, mobile thing." Both the Earth's surface and its interior are in motion. Below the lithospheric plates, at some depth the mantle is partially molten and can flow, albeit slowly, in response to steady forces applied for long periods of time. Just as a solid metal like steel, when exposed to heat and pressure, can be softened and take different shapes, so too can solid rock in the mantle when subjected to heat and pressure in the Earth's interior over millions of years."http://pubs.usgs.gov/gip/dynamic/unanswered.html\nThe website below will give you illustrations and discusses both continental drift and plate tectonics.
797755
It happens in the brittle part of the crust, which is not usually deeper than 20 km.\n\nHere's the jist:\n\nIt all comes down to stress and strain. It is not 'the plates rubbing together' as many people say; or at least that's a very simplistic view.\n\nPlate tectonics causes stress on the continents and oceans, all over the surface of the earth. In some places, the stress is very small (usually within the plates). Elsewhere, the stress is high, usually where the plates meet each other. Since each plate moves, when two come in contact, the stress each other. They can push on each other and cause compressional stress, they can pull with extensional stress, and they can slide past or shear each other with tensional stress.\n\nFaulting, causing earthquakes, comes from the fact that this stress is building up all the time, but rocks and continents are strong materials. Just like hitting a rock with a small hammer, you do put stress on it, but a small amount. It would take a sledgehammer to put enough strain (effects and accumulation of stress) to build up and cause breakage. In the earth, the area around an active fault builds up strain from the stress of plate tectonics. Most faults become locked, because of this strength, and thus can not release their strain. Away from the fault, the stress produces very small and slow movement of the rock masses as a whole. Eventually, the strain is too much and the rest of the plate has moved too far and the fault releases the strain build-up all at once in a big stress release called an earthquake. This is called the elastic rebound theory, and it explains most (but not all) movements.\n\nThis is why an earthquake's size is relative to the fault size. The bigger the fault, the bigger the strain build up, and the bigger the release in an earthquake. Subduction zones and collision zones, where large portions of plates actually can rub together as a whole, have the really big earthquakes, like the 2004 Sumatra earthquake. In other plate boundaries, the entire plate boundary does not act together, so the faults become spread out and many faults take up the strain from the tectonic stress, like with the San Andreas Fault in California (it only takes up ~3/4 of the stress between the plates).\n\nEarthquakes are really tricky things; there is still so much we need to learn. As of now, there is no way to predict them, but we can say where the danger is highest and about how long between events.
712469
The earth's crustal plates float on a layer called the Mantle, and it is convection in this mantle which drives the continental drift or plate tectonics.
383515
In a subduction zone, one plate is being pulled under another. When continental crust & oceanic crust are involved, the oceanic crust is subducted b/c it is denser.\n\nThis type of stress is called compressional stress.\n\nIn the case of ocean ridges, like that found in the middle of the Atlantic Ocean, they are being pulled apart. That is a tensional stress. New crust is constantly being created there.\n\nIn the case of the San Andreas Fault, which is in the news a lot lately, it is two plates that are moving laterally. They are sliding past each other. This is a shearing stress.