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billion of years ago , Earth ’s airfoil was a ocean of molten rock . As this simmer magma gradually cool off , it make a continuous , stony cuticle , with the denser mineral coalescing toward the planet ’s interior and the less - dense mineral uprise to the surface .
" That is how the denture make at the surface of theEarth,“Catherine Rychert , a geophysicist at the Woods Hole Oceanographic Institution in Massachusetts , say Live Science . " The plate is the crust , then a bit of the mantle beneath it … . Beneath that you have weaker material . "
Here we see some of the major and minor tectonic plates on Earth today.
This light material is hotter and mobile . The difference in strength between these bed is what allow the overlying plates to move — clash , diverging and grating against one another . In these zone , rift and mountains form , andvolcanoesandearthquakesspark to life .
But how many of these plates cover Earth ’s surface ? The solution grade from a twelve to closely 100 , depending on how you look at it .
link up : What ’s inside Earth ?
Here we see some of the major and minor tectonic plates on Earth today.
Mostgeologistsagree that there are between 12 and 14 " primary " plate that insure most of Earth ’s surface , saidSaskia Goes , a geophysicist at Imperial College London . Each has an area of at least 7.7 million square miles ( 20 million square kilometer ) , with the largest being the North American , African , Eurasian , Indo - Australian , South American , Antarctic and Pacific plate . The most massive of these is the Pacific Plate , which spans a thumping 39.9 million square miles ( 103.3 million substantial km ) , closely followed by the North American Plate , which covers 29.3 million square nautical mile ( 75.9 million square kilometer ) .
" In plus to the seven very turgid [ plate ] , there are five more pretty smaller one : Philippine Sea , Cocos , Nazca , Arabian and the Juan de Fuca , " Goes told Live Science . Some geologists count the Anatolian Plate ( part of the large Eurasian Plate ) and the East African Plate ( part of the African Plate ) as separate entities , " as they are moving at amphetamine that are clearly dissimilar from these independent scale , " Goes say . That explain why the main collection plate idea ranges from 12 to 14 .
thing grow more complicated when you look at plate boundaries , whereplate tectonicscauses plates to splinter into small fragments calledmicroplates . These have an orbit ofless than 386,000 satisfying air mile ( 1 million straight km ) , and some scientists estimate that there are about57on Earth . But they unremarkably are n’t included on humankind single-valued function — a disagreement that reflects some uncertainty about how they form .
" The number of microplates will keep on changing , depend on how dissimilar scientist choose to fix them , and as we learn more about how and where the deformation at collection plate boundaries localizes , " exit say .
— When did Antarctica become a continent ?
— What is the rarest mineral on Earth ?
— How large is the largest possible quake ?
As geologists make sense of this active puzzle , Earth ’s moving plate create some enchanting scenarios . The Pacific Plate is probably the fastest , moving northwest 2.8 to 3.9 column inch ( 7 to 10 centimeters ) per yr , Rychert say .
" The flying motion is cause by a surrounding ring ofsubduction zones , otherwise known as the Ring of Fire , where gravitative forces are pulling the plates down into the ground , " she said , total that the unremitting motion may even be consuming continents . " We cogitate that sometimes continents founder , and a small-arm will really pass off into the Mickey Mantle , " Rychert said .
With these spectacular power at play , what our satellite ’s plate - encrusted surface will look like another few billion years from now remains a mystery .
