Why does the earth have continents?

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observation paul's information. is, sadly, dead wrong. pangaea not formed @ time of appearance of water on earth. pangaea latest in series of supercontinents have been proposed existing during our planet's history. recent have been named rodinia, pannotia, and, before pannotia, columbia.the evidence pretty three. other, prior, superc's have been proposed also, data squirrely after go 3 billion years or so.

can't imagine why!

pangaea formed 270 million years ago, , broke see today our continental masses after that. breakup got high gear around 200 years ago. is, interestingly, long after fishes , amphibians , reptiles had developed, , while reptiles beginning "run" of dominance on planet. indeed, evidence existence of pangaea includes distribution of closely relates species of reptiles on several continents.

continental formation... tplate formation...the crust of planet not of uniform strength across entire surface. convective forces in mantle put pressure on crust, , on occasion breaks, allowing plates form. of plates include lighter, continental crust. of plates contain denser, oceanic crust. contain of both kinds of crust.

latter fact why makes no sense talk continental "drift." continents don't drift. tectonic plates move. carry continents them, if plate happens have continental crust on it. plates, pacific plate, nazca plate, juan de fuca plate don't have continental crust on them. plates, european plate or asian plate, have lot of continental (light) crust on them.

if want reasonable analogy why plates (or continents) form do... go watch surface ice break on pond in late winter/early spring several years. record how breaks each year. plot shape , size , location of various blocks of ice. vary widely, year year. why? because ice not of uniform strength when water under moving around , putting pressure on floating ice.

same tectonic plates? kinda. not completely. close enough work illustration.

go usgs site , read. , learn. it's fascinating.

http://pubs.usgs.gov/gip/dynamic/dynamic...

what caused continents form? also, why aren't there on other planets?


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