Continent with other islands in the Pacific into one continent called Oceania. This divides the entire land surface of Earth into continents or quasi-continents. The ideal criterion that each continent is a discrete landmass is commonly relaxed due to historical conventions. Of the seven most globally recognized continents, only Antarctica and Australia are completely separated from other continents by the ocean. Several continents are defined not as absolutely distinct bodies but as ""more or less" discrete masses of land". Asia and Africa are joined by the Isthmus of Suez, and North and South America by the Isthmus of Panama. In both
Geological history of Earth (approximately ) during which a large number of impact craters are believed to have formed on the Moon, and by inference on Earth, Mercury, Venus and Mars as well. The Earth of the early Archean () may have had a different tectonic style. During this time, the Earth's crust cooled enough that rocks and continental plates began to form. Some scientists think because the Earth was hotter, that plate tectonic activity was more vigorous than it is today, resulting in a much greater rate of recycling of crustal material. This may have prevented cratonisation and continent formation until the mantle