Is old rock really 'as solid as a rock'? Deformed craton under North America
Monday, September 7, 2015 - 21:00
in Earth & Climate
In the course of billions of years continents break up, drift apart, and are pushed back together again. The cores of continents are, however, geologically extremely stable and have survived up to 3.8 billions of years. These cores that are called cratons are the oldest known geological features of our planet. It was assumed that the cratons are stable because of their especially solid structure due to relatively low temperatures compared to the surrounding mantle. Now researchers have discovered that the craton below the North American continent is extremely deformed: its root is shifted relative to the center of the craton by 850 kilometers towards the west-southwest.