The Principle of Isostasy

This video provides a demonstration of the principle of isostasy, the idea that the continental crust “floats” on the underlying mantle.

Using weights and a piece of foam, geologist Naomi Oreskes demonstrates how continents rose in elevation after ice sheets from the last ice age retreated. The rise in Earth’s crust suggested that the underlying mantle is pliable.

This clip is from a 2012 Holiday Lecture Series, Changing Planet: Past, Present, Future.