Afro-Eurasia

Afro-Eurasia (also called Afroeurasia or Eurafrasia) is a landmass sometimes referred to as a supercontinent, made up of Africa, Asia, and Europe. Its name is a blend of those three continents. It is also known as the "Old World," a term used to distinguish it from the "New World" of the Americas, and sometimes Oceania and Antarctica. Covering 85,135,000 square kilometers—57% of Earth's total land—it is home to about 6.7 billion people, or roughly 86% of the global population. Along with mainland Australia, it forms the vast majority of land in the Eastern Hemisphere. This contiguous landmass is the largest and most populous on the planet.

Several related terms exist. "Ecumene" comes from classical antiquity and referred to the world known to ancient Greek scholars, which included only Europe and parts of Africa and Asia. "Old World" emerged during the Age of Discovery, when European explorers contrasted their familiar lands with the newly encountered Americas; it remains common in biology. "World Island" was coined by geographer H.J. Mackinder in 1904 for geopolitical use, describing the large contiguous landmass while excluding islands like the British Isles, Japan, Madagascar, and the Malay Archipelago. "Afro-Eurasia," however, generally includes those islands when they are considered part of Africa, Asia, or Europe.

Geologically, Afro-Eurasia is not a true supercontinent but rather the largest current segment of the supercontinent cycle. Its oldest known part is the Kaapvaal craton, which, together with Madagascar, parts of India, and western Australia, formed the early supercontinent Vaalbara or Ur about 3 billion years ago. This region has been part of every supercontinent since. When Pangaea broke up around 200 million years ago, the North American and Eurasian plates formed Laurasia, while the African plate stayed in Gondwana. The Indian plate later split from Gondwana, collided with the Eurasian plate around 50 million years ago, creating southern Asia and beginning the uplift of the Himalayas. Around the same time, the Indian plate fused with the Australian plate. The Arabian plate separated from Africa about 30 million years ago and collided with the Iranian plate between 19 and 12 million years ago, forming the Alborz and Zagros mountain chains. Shortly after this initial connection of Afro-Eurasia, the Betic corridor along the Gibraltar Arc closed nearly 6 million years ago, linking northwest Africa and Iberia and causing the near-total drying of the Mediterranean Basin—the Messinian salinity crisis. Eurasia and Africa were separated again about 5.33 million years ago when the Zanclean Flood refilled the Mediterranean through the Strait of Gibraltar.

Today, the Eurasian and African plates dominate their respective continents. The Somali plate covers much of eastern Africa, creating the East African Rift. In the eastern Mediterranean, the Aegean Sea, Anatolian, and Arabian plates border the African plate, which includes the Sinai Peninsula, Gulf of Aqaba, and the coastal Levant via the Dead Sea transform. Eurasia also contains the Indian, Burma, Sunda, Yangtze, Amur, and Okhotsk plates, while the North American plate includes the Chukotka Autonomous Okrug in Russia’s Far East. By convention, Africa is connected to Eurasia only by a narrow land bridge (now split by the Suez Canal at the Isthmus of Suez) and remains separated from Europe by the straits of Gibraltar and Sicily.

Looking ahead, paleogeologist Ronald Blakey considers the next 15 to 100 million years of tectonic development fairly predictable. Africa will continue drifting northward, closing the Strait of Gibraltar and quickly evaporating the Mediterranean Sea. No supercontinent is expected to form within that timeframe, and the geologic record shows unexpected shifts that make further projections highly speculative. Three possible future supercontinents—Novopangaea, Amasia, and Pangaea Proxima—have been proposed. In the first two, the Pacific closes while Africa remains fused to Eurasia, but Eurasia splits as Africa and Europe spin westward. In the last, the trio spins eastward together as the Atlantic closes, creating land borders with the Americas.

Extreme points of Afro-Eurasia are as follows. On the mainland: the easternmost point by longitude is the 180th meridian in Russia; on a continuous eastbound path, it is Cape Dezhnev, Russia. The northernmost point is Cape Chelyuskin, Russia; the southernmost is Cape Agulhas, South Africa; the westernmost is Pointe des Almadies, Senegal. Including islands: the easternmost point is Big Diomede, Russia (the 180th meridian passes through Asia, so this point lies in the Western Hemisphere and is Asia’s easternmost on a continuous path). The northernmost is Cape Fligeli on Rudolf Island, Franz Josef Land, Russia. The southernmost remains Cape Agulhas, South Africa; if the Prince Edward Islands are included in Africa, then Marion Island at 46°54'S is the southernmost. The westernmost is Santo Antão, Cape Verde. The highest elevation is Mount Everest on the China–Nepal border, at 8,848.86 meters above sea level. The lowest point on land is the shore of the Dead Sea, between Israel, the West Bank, and Jordan, at 430.5 meters below sea level.