Gravitational Anomalies Beneath Mountains Point To Isostasy of Earth's Crust

StartsWithABang writes: Imagine you wanted to know what your acceleration was anywhere on Earth; imagine that simply saying "9.81 m/s^2" wasn't good enough. What would you need to account for? Sure, there are the obvious things: the Earth's rotation and its various altitudes and different points. Surely, the farther away you are from Earth's center, the less your acceleration's going to be. But what might come as a surprise is that if you went up to the peak of the highest mountains, not only would the acceleration due to gravity be its lowest, but there'd also be less mass beneath your feet than at any other location.

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Re:We've known that mountains 'float' for a long t

[Eravnrekaree]

All of the earth crust floats. Mountains are higher because the rock beneath them is lighter, hotter, or thicker than elsewhere. Continental crust does not subduct because it is the result of island arc subduction related magmatism which produces metal poor rocks due to fractional melting, producing a rock that is lighter than mantle. Oceanic crust is mafic and contains more metals, is more dense, and has similar composition to the mantle, so it tends to subduct easily. Good we are covering basic geology 101 for the benefit of all here.