Laurentia

Laurentia, also called the North American craton, is the ancient continental core of North America. It first assembled around 2.0 to 1.8 billion years ago from a group of Archean crustal fragments, including the Slave, Rae-Hearne, Superior, Wyoming and Nain cratons, welded together along the Trans-Hudson orogenic belt. It contains some of Earth's oldest known rock, the Acasta Gneiss, dated to 4.04 billion years. In Canada the craton is exposed at the surface as the Canadian Shield, while across much of the United States it lies buried beneath younger sedimentary rock. Laurentia has repeatedly been part of larger supercontinents, including Rodinia and Pangaea, before emerging again as the stable core of the modern North American continent.