Laurentia

Laurentia is the Precambrian core of North America, a stable continental craton that underlies a large portion of the North American Plate. The term refers to the ancient crust that forms the Canadian Shield and adjacent regions of eastern and central North America. The name historically links to early geological study of rocks around the Saint Lawrence region.

Geological history and formation: Laurentia formed through the accretion of multiple Archean and early Proterozoic crustal blocks between about 3.0 and 2.0 billion years ago and grew during subsequent Proterozoic assembly events. The Grenville Orogeny, roughly 1.3 to 0.9 billion years ago, welded many of these blocks into a coherent craton. The interior of Laurentia has remained relatively stable since then, even as peripheral regions experienced later orogenic activity that built mountain belts along the margins.

Palaeogeography and later evolution: In the late Precambrian and early Paleozoic, Laurentia existed largely as a separate landmass. During the formation of the supercontinent Pangaea in the late Paleozoic, Laurentia joined with other landmasses to occupy the northern portion of the assembly. After the break-up of Pangaea in the Mesozoic, Laurentia became the core of the modern North American Plate.

Geology today: The Laurentian craton underlies much of Canada and parts of the northern United States and forms the Canadian Shield. Its ancient rocks include granites, metamorphic complexes, and greenstone belts, regions that are important for understanding Earth's early crust and mineral resources.