At times in the past, Laurentia has been part of larger continents and supercontinents. It is an assembly of smaller tectonic plates which merged early in the Archaean era. As the plates moved together, a huge range of mountains formed. Much later, in the Proterozoic era, small plates and oceanic islands collided with and fused with the ever-growing Laurentia. Together they made the huge, stable craton we see today as the north and center of North America and the west of Greenland. 