How many tectonic plates make up the crust of the earth?
477451
Current major plates:\n\nAfrican Plate \nAntarctic Plate \nArabian Plate \nAustralian Plate \nCocos Plate \nEurasian Plate \nIndo-Australian Plate \nIndian Plate \nNazca Plate \nNorth American Plate \nPacific Plate \nPhilippine Plate \nScotia Plate \nSouth American Plate \n\nCurrent minor plates:\n\nAdriatic Plate \nAmurian Plate \nAnatolian Plate \nBismark Microplate \nBurma Plate \nCaribbean Plate \nCaroline Plate \nEast American Plate \nEaster Microplate \nExplorer Plate \nFiji Microplates \nGalapagos Microplate \nGorda Plate \nHellenic Plate \nIberian Plate \nIranian Plate \nJuan de Fuca Plate \nJuan Fernandez Microplate \nOkhotsk Plate \nRivera Microplate \nSomali Plate \nSouth Sandwich Plate \nSunda Plate \nTonga Plate \n\nAncient plates:\nFarallon Plate \nKula Plate
1101902
The continents are the great land masses of the earth. There are seven continents on Earth now: Africa, Antarctica, Asia, Australia, Europe, North America, and South America. \nThere are seven continents on Earth now. \nAsia and Europe are not separate land masses. They are divided by the Ural Mountains. \n\nThere are no countries in Antarctica. The U.S. and many other countries operate science stations there, but no nation owns the land. \n\nSee maps and much more in\nhttp://www.enchantedlearning.com/geography/continents/
707879
The tectonic plates are "floating" on a liqid mantle that has convection currents.  These convection move the plates around the globe.  This is the science behing plate tectonics
1117362
tectonic plates or continental drift
45616
Fractured crust is the collective term for tectonic plates.
1033087
This is a direct quote from the website (see below)\nBackground\nGeologists believe that a super-continent composed of all of the present day continents existed on the planet\n200 million years ago (at the same time dinosaurs were on earth). Geologists call this super-continent\nPangaea. Because there was only one continent, there was only one ocean called Tethys.
134043
Plate Tectonics is actually the science that studies the Earth's (or any other planet's, for that matter) tectonic plates.
1081316
The reponse is related to plate tectonics. The earth crust is composed of a larger number of plates that float, very slowly of course, over the liquid interior. Continents therefore move relative to each other. When two plates meet, generally one moves under the other and it is here that we find mountains and volcanoes.\n\nWhat relation with oceans? Well, between some of the plates there is an upwelling of new magma, new crust. This is for instance the case in the middle of the Atlantic Ocean. The new crust needs room and pushes the plates on the left and right away: the Americas are moving to the west, while Europe and Africa are moving to the east. \n\nOceans (ah, at last!) are watermasses in which such upwelling of fresh crust takes place. An ocean therefore is partly in two or more different plates. On the other hand, seas are bodies of water that are on one continental plate only, or on two plates were no new crust is formed.\n\nHere is a pictures of the different continental plates:\n http://en.wikipedia.org/wiki/Image:Plates_tect2_en.svg
435645
A, because it's the division between two tectonic plates. the plates move apart and magma from inside the earth comes up and piles up in the form of mountains.
74194
Transform boundaries -- where crust of the earth\nis neither produced nor destroyed as the plates slide horizontally past each other
967662
It 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.
59451
Plate tectonics is the answer to your questions about weathering and erosion, as well as thickness of the continental crust. Plate tectonics moves and lifts continental plates continuously, and faster than erosion can carry the sediments away. Mt. Everest is a good example of this, as pressure from the adjoining crustal plates is lifting the mountain at a rate of a few centimeters a year. \n\nAs this pressure against the continental plates builds they often fold and break, and this causes parts of the contintal plates to slide up over other parts of the plate, making them thicker that the oceanic plates. \n\nAt present the only way to find the top of the mantle is using seismology. Siesmologists measure the way that shock waves (sound waves) move through the earth when earthquakes happen. By studying the way these sound waves are deflected from different rocks they can tell about how deep the boundary is between the crust and the mantle. \n\nHere is one of the best websites that explains plate tectonics. It has animated illustrations that show moving plates and how they have changed over time:\nhttp://www.ucmp.berkeley.edu/geology/tectonics.html
1128821
tectonic plates are giant pieces of the Earth's crust.  They "float" on the mantle, a layer of liquid rock under the crust.  The plates are constantly moving.  A mountain range is formed when two plates moving toward each other collide.  One plate will "run over" the other.  When this happens the top plate gets pushed up and the bottom pushed into the mantle.  The top plate will rise to form a mountain range.\n\nClimate and erosion give the mountain range its finished look (paint on the car).  The tectonic movement gives it its general shape.
33502
None, but there are nine planets in the solar system that Earth is part of.
836192
The Earth is formed of several layers that have very different physical and chemical properties. The outer layer, which averages about 70 kilometers in thickness, consists of about a dozen large, irregularly shaped plates that slide over, under and past each other on top of the partly molten inner layer. Most earthquakes occur at the boundaries where the plates meet. In fact, the locations of earthquakes and the kinds of ruptures they produce help scientists define the plate boundaries. \nThere are three types of plate boundaries: spreading zones, transform faults, and subduction zones. At spreading zones, molten rock rises, pushing two plates apart and adding new material at their edges. Most spreading zones are found in oceans; for example, the North American and Eurasian plates are spreading apart along the mid-Atlantic ridge. Spreading zones usually have earthquakes at shallow depths (within 30 kilometers of the surface).  \n\nTransform faults are found where plates slide past one another. An example of a transform-fault plate boundary is the San Andreas fault, along the coast of California and northwestern Mexico. Earthquakes at transform faults tend to occur at shallow depths and form fairly straight linear patterns. \n\nSubduction zones are found where one plate overrides, or subducts, another, pushing it downward into the mantle where it melts. An example of a subduction-zone plate boundary is found along the northwest coast of the United States, western Canada, and southern Alaska and the Aleutian Islands. Subduction zones are characterized by deep-ocean trenches, shallow to deep earthquakes, and mountain ranges containing active volcanoes.\n\nEarthquakes can also occur within plates, although plate-boundary earthquakes are much more common. Less than 10 percent of all earthquakes occur within plate interiors. As plates continue to move and plate boundaries change over geologic time, weakened boundary regions become part of the interiors of the plates. These zones of weakness within the continents can cause earthquakes in response to stresses that originate at the edges of the plate or in the deeper crust. The New Madrid earthquakes of 1811-1812 and the 1886 Charleston earthquake occurred within the North American plate.
1000213
Plate tectonics moves continents around in a cyclic pattern known as the Wilson Cycle. In about 250 million years in the future, we will again have a supercontinent.\n\nThe Paleomap Project has predicted what the earth will look like based on current evidence. The Atlantic Ocean will no longer exist, as North American will be forced up against Africa and Europe, and Indian Ocean may only remain as an inland sea.  Antarctica will again be at the South Pole and Australia will be pushed up against it. The southern part of South America will be adjoining Indonesia. \n\nThe area where the south Pacific is now is likely to have some new volcanic islands, but probably all of the currently existing islands will have been pushed up against a continent. The Pacific Ocean will be much larger than today and will cover half of the earth. \n\nHere is a map:\nhttp://www.scotese.com/future2.htm\n\nI would speculate that even further in the future as the supercontinent breaks up, it is likely that some portion of the supercontinent will move towards the South Pacific. \n\nVolcanism plays an important role in building continental plates, and is constantly adding continental material, but continental plates are composed primarily of less dense intrusive igneous rocks such as granite. Volcanoes produce extrusive igneous rocks, which do not make up the major parts of the continental land masses so volcanoes are not as important in continent building as other processes.  \n\nHere's a site that explains the Wilson Cycle:\nhttp://csmres.jmu.edu/geollab/fichter/Wilson/Wilson.html
1148782
What Is It?\nScientists have learned that the Earth's crust is fractured into a series of "plates" that have been moving very slowly over the Earth's surface for millions of years. Two of these moving plates meet in western California; the boundary between them is the San Andreas fault. The Pacific Plate (on the west) moves northwestward relative to the North American Plate (on the east), causing earthquakes along the fault. The San Andreas is the "master" fault of an intricate fault network that cuts through rocks of the California coastal region. The entire San Andreas fault system is more than 800 miles long and extends to depths of at least 10 miles within the Earth. In detail, the fault is a complex zone of crushed and broken rock from a few hundred feet to a mile wide. Many smaller faults branch from and join the San Andreas fault zone. Almost any road cut in the zone shows a myriad of small fractures, fault gouge (pulverized rock), and a few solid pieces of rock.