IF YOU happen to find yourself on the Mediterranean Sea, take a minute to observe the shore. Watch closely for a while (for a year, to be precise), and you might notice it budge slightly (about 2cm, or a little less than an inch). Africa and Europe are slowly colliding in a process that has lasted for 40m years, pushing up the Alps and Pyrenees along the way. This continental drift will continue long into the future, until 50m years from now when the two continents meet and become one mega-continent: Eurafrica. The Mediterranean will disappear altogether, to be replaced by a mountain range as big as the Himalayas. It will be an unrecognisable world.

Continental drift is a relatively recent addition to the geological canon, and was only widely accepted in the 1960s. The tectonic plates underneath the Earth are constantly moving, dragged around by convection currents in the planet’s mantle. In recent years scientists have gained a good understanding of how continents used to move: they now theorise that multiple super-continents have been created in cycles over the course of Earth’s history. The most recent such landmass, Pangea, broke up approximately 200m years ago, meaning the Earth is currently in the middle of a cycle. Extrapolating from historical data allows researchers to forecast what might be in store.

The next 50m years are relatively easy to predict, and most geologists agree that the Mediterranean will close. The fate of other seas and oceans is very much up for debate, though. The best-known prediction comes from Christopher Scotese, a geologist at the University of Texas. His “introversion” theory suggests that the Atlantic, which is currently widening, will eventually start to reverse course. Over the next 200m years it will slowly close, he suggests, and the Americas will collide with Eurafrica to form Pangea Proxima. Others think the exact opposite might happen: the Atlantic will continue to widen while the Pacific closes, with California eventually colliding with far-east Asia. A frostier forecast holds that all the continents will move north, closing up the Arctic ocean and forming “Amasia” around the North Pole. Earlier this year a rather different prediction was proposed by João Duarte at the University of Lisbon. His team think the evidence indicates that both the Atlantic and Pacific oceans could close. To resolve the spatial conflict that would create, they suggest Asia will cleave in two, ripped apart along the India/Pakistan border. A new Pan-Asian ocean would form in the space, becoming the world’s largest ocean, while “Aurica” (an assemblage of all the world’s existing land masses) would be created in the middle of what was once the Pacific.

Forecasting geological events 200m years ahead is clearly not an exact science. These scientists are in the enviable position of being able to say things that will never be disproved by mankind, as it is unlikely that humanity will be around to see the next super-continent form. Nevertheless, such contemplations of the future are rather sobering: a reminder that the land beneath our feet is ultimately little more permanent—on a geological scale—than the borders we draw on its surface.