Yeah I have no idea what they are referencing either. Ice sheets are called as such because they sit on top of the continents. Apparently North America was actu

Yeah I have no idea what they are referencing either. Ice sheets are called as such because they sit on top of the continents. Apparently North America was actually compressed downwards by the last sheet and is still basically rising back up. Maybe they are thinking of permafrost or something? I'm not sure how deep that gets at the Northern reaches like Svalbard. But most of the land on earth is not permafrost for a long time now.