We do have some idea what happens - post-glacial rebound is very noticeable in some parts of the world that were heavily glaciated in the last ice age: https:/

We do have some idea what happens - post-glacial rebound is very noticeable in some parts of the world that were heavily glaciated in the last ice age: https://en.wikipedia.org/wiki/Post-glacial_rebound https://en.wikipedia.org/wiki/Post-glacial_rebound