Notable examples are Zealandia, rising from the ocean primarily in New Zealand and New Caledonia,[non-tertiary supply needed] and the virtually completely submerged Kerguelen Plateau in the southern Indian Ocean. Apart from the present continents, the scope and meaning of the term continent includes previous geological ones. Supercontinents, largely in evidence earlier in the geological record, are landmasses that comprise more than one craton or continental core. These have included Laurasia, Gondwana, Vaalbara, Kenorland, Columbia, Rodinia, and Pangaea. Over time, these supercontinents broke apart into giant land lots which shaped the current continents. For a more detailed list of populations by continental regions and subregions, see List of continents and continental subregions by population.
During the cool occasions, glaciers coated a lot of the land in the northern hemisphere. Plants and animals had to migrate southwards to keep away from the ice and cold temperatures. In North America the mountains are aligned primarily north-south, so species may migrate on the west and east sides to more southerly climes. We know this because when scientists analyze soil cores extracted from lakes and bogs in the south, they discover pollen grains of species that right now develop only in the north, such as purple spruce and jack pine. Extraregional immigrants are typically extra susceptible compared to regional migrants, as they have a tendency to face challenges associated to accessing regular migration standing , as properly as language and cultural barriers, among others . Extraregional migrant flows are composed primarily of refugees/asylum seekers, economic migrants and irregular migrants .