Expert: Courtney Seligman - 11/14/2008

Question
Hello.


  According to True Polar Wander theory, if a supersized volcano is on earth, then our planet would tilt and rotate itself (over a period of 5 Ma years or 20 Ma years) until this volcano is near the equator.

I think that this is due to the fact that this supersized volcano didn't have a deep crustal root (like icebergs) to support its huge weight, so it devitated the center of gravity so much that the Earth, to be balanced back, tilted.

Therefore, if continental mountains (ie, ONLY mountains formed through crustal thicknening, such as Urals, Alps, Himalaya, Pyrennes) lose their crustal deep roots (that support their weights), then would they provoke a true polar wander, like the supersized volcano?


Thank you

Answer
If it were possible for large structures (supersized volcanoes or continents) to not have deep roots, it would be possible for the Earth's crust to change its position, relative to its current orientation. But I can't imagine any way in which this could happen, particularly for the continents, since their roots are made of lighter materials than the surrounding mantle material. And even the material below a supersized volcano would be hot and "plastic" (deformable), so it is hard to imagine it remaining without deep roots for periods long enough to significantly rotate the surface of the Earth. Long before then, erosion and subsidence should almost completely remove any gravitational differential exceeding a few tens or hundreds of feet.

So although, given a sufficiently improbable hypothesis, such a thing might be possible, I seriously doubt anything like this could actually happen. However, you might want to consult a geologist or geophysicist, for another opinion.

Courtney Seligman