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Is there some evidence for this based on gravity anomalies? I think I know how to tell if a mountain or structure is compensated based on bougeur and free air anomalies, but this really has me stumped? Does this somehow tie into how underwater mountains are compensated by pratt rather than airy?

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    $\begingroup$ Where did you get the idea that continents sink? Basically (and really simplistically) continents are lighter rock that "floats" around on the mantle. Some continental rocks have been around for several billion years news.mit.edu/2011/stable-continents-0106 while little if any of the ocean crust has been around for more than 300 million earthobservatory.sg/faq-on-earth-sciences/… $\endgroup$ – jamesqf Feb 10 '18 at 19:36
  • $\begingroup$ Thanks, those links are really helpful. This is a question my geophysics professor gave to work on over the weekend, essentially he wants me to disprove the idea that oceanic crust is really sunken continental crust. I'm not 100% sure what he is getting at though. $\endgroup$ – spinelcity Feb 10 '18 at 20:54
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    $\begingroup$ Perhaps the idea is that the mostly basaltic ocean crust is denser than continental rock, and this could be detected by gravity measurements? I'm not a geophysicist, though. $\endgroup$ – jamesqf Feb 11 '18 at 3:25
  • $\begingroup$ Counter-counter argument: Zealandia. $\endgroup$ – David Hammen Feb 11 '18 at 17:18
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    $\begingroup$ @David Hammen: However, is there evidence that Zealandia actually sank, rather than (as the link says) just having thinner continental crust than other continents, so that much of it is often below the changing sea level? Compare for instance the area of the continental shelves that was above sea level in the last Ice Age: iceagenow.com/Sea_Level_During_Last_Ice_Age.htm $\endgroup$ – jamesqf Feb 11 '18 at 20:32

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