Laurentia is a geologically old continental block that large parts of present-day North America, including Greenland covers.
The Acasta - gneiss from the western Canadian Shield dating from the Hadean of 4,030 mya and possibly up to 4.3 billion years old Nuvvuagittuq greenstone belt from the eastern Canadian Shield: In the land mass Laurentias the oldest rock formations on the planet were found.
Laurentia was about 1,910 mya from that part of the fragments Kenorlands that caused the Wopmay - orogenesis in the Slave Province of the Northwest Territories, and was from about 1,100 mya part of the supercontinent Rodinia.
About 800 mya to Laurentia split again from Rodinia. With the rest of Proto- Laurasia, whose part Laurentia was, it moved during the Ediacarian slowly to the north, and probably still united again briefly with the remaining parts of the earth to Pannotia. Now it can also be designated as part of Laurasia.
To 440 mya, in the early Silurian, the Iapetus Ocean began east of Laurentia expand. His plate subducted under the East Coast, raised the continental crust and resulted in a period of volcanism. The Appalachian Mountains formed on Laurentia, while growing at the same time on the other side of the sea, on the already combined Baltica / Avalonia, the Caledonian Mountains. Sedimentary rocks of the Iapetus Ocean, are now detectable in both mountain ranges. In the early Devonian, about 400 mya, the Iapetus Ocean then joined to an inlet of the ocean Rheischen and so welded the three continental plates to new super continent Laurussia or Euramerica. The Appalachian and Caledonian mountains were raised further.
To 300 mya was the newly emerged Euramerica with the other great continents of Asia and Gondwana supercontinent Pangaea to date last.