• Question: Will any of earth's plates just sink into the mantle?

    Asked by to Anna, Elaine, Fiona, Kevin, Darren on 17 Jun 2014. This question was also asked by .
    • Photo: Kevin O'Dell

      Kevin O'Dell answered on 17 Jun 2014:

      I feel this is a ‘phone a friend’ moment. My (very limited) understanding is that this is happenning already in that some plates are sinking under others. Whether this means they’ll disappear altogether I don’t know. But I suspect there are geologists around who would be able to make fairly accurate predictions about this.

    • Photo: Elaine Cloutman-Green

      Elaine Cloutman-Green answered on 19 Jun 2014:

      For the same reason that bubbles don’t sink in bubble bath. Although the rocks of the crust seem heavy to us, they are pretty light on average when compared to the iron core or the mantle. The density of the crust is about 3 grams per cubic centimeter. The mantle goes up to about 5.5 and the core is around 12 grams per centimeter and heavier still in the middle. The lightest bits (including rocks and us) float on top.

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