What's a continent? How many of them are there? Why are there five rings on the Olympic Flag to represent seven continents? Is Greenland part of North America? Is Central America part of North America? Why is Australia a continent but Greenland isn't? What continent does New Zealand belong to? These are some of the questions which show that people are confused by the whole subject of continents.

Continents are an arbitrary way of dividing up the world's landmasses and they don't have any strict scientific basis, so they have been assigned in different ways over the years.

Dividing the World Into Three

The really ancient Greeks divided the world into three: Europe, Asia and Libya, based on the small part of the globe that they could reach in their small boats. They thought of each of these regions as entirely separated by sea from the others, since they hadn't yet sailed far enough to find the places where the three landmasses joined together. Europe was clearly separate from Asia as far as the Greeks were concerned because the Bosporus channel separated them. If you sailed up the Bosporus, you could reach open sea, which they thought was part of the Great Ocean which surrounded the whole world. Further exploration eventually showed that the three landmasses were connected.

By the 13th century, the world was considered to have three continents, Europe, Asia and the big southern continent. The north coast of this continent, on the Mediterranean Sea, was divided into two - the western end was called Africa and the eastern end was Libya. Somewhere along the way the name Africa started to be used for the whole continent. The border between Asia and Africa was pretty clear because there's a narrow section only 130km wide between the Red Sea and the Mediterranean Sea. The border between Europe and Asia was not so clear. In the south the two continents are still separated by the Bosporus (or Bosphorus) channel, but north of the Black Sea, it's somewhat arbitrary where you draw the line. The Ural Mountains which go most of the way from the Black Sea to the Arctic have traditionally formed the border between Europe and Asia, but south of the Urals it's not so clear. Some would consider the Volga river to form the border.

A New World - the Fourth Continent

In 1492, Christopher Columbus officially became the first person to discover a new continent - it somehow got named America rather than Columbia. But the name America applied to everything from the north of Canada to the south of Argentina and it was all considered to be one continent.

A New Southern Continent

People noted that most of the continents are in the northern half of the world. To balance this, they thought there must be a giant continent in the south. They drew it on maps and called it the "Unknown Southern Land" (Terra Australis Incognita in Latin). They sent explorers off to find it and eventually they did find a big land, although not as big as they had expected. Was this Terra Australis Incognita? Not exactly, but the name Australia became attached to the new land and it became a fifth continent.

As late as the early 20th Century, schoolchildren were being taught in England that there were five continents: Europe, Asia, Africa, America and Australia (probably in that order, too!). When the modern Olympic Games were set up at the end of the 19th century they designed a flag with five coloured rings to represent the five continents, although I don't think that any ring represented any particular continent.

Splitting America Into Two

At some point people realised that America was really two separate landmasses, joined by a narrow isthmus only 50 kilometres wide, so the names North America and South America started to be used. North America is Canada, the United States of America, Mexico and all those little countries south as far as Panama. So this answers one of the questions given above - Central America is a region within the continent of North America.

South America starts at the border between Panama and Colombia.

The Last Continent

It's a fact that the continent of Antarctica was discovered by the same guys who discovered Australia, but they didn't initially realise it was a continent. They thought it was just ice floating on the sea, like the ice that floats above the North Pole. Of course they could see some land, but they thought this was just islands in the ice. It's interesting how recently this belief was still around - Jules Verne writing in 1871 in his book Twenty Thousand Leagues Under the Sea allowed Captain Nemo to go to the South Pole under the ice in his submarine, the Nautilus.

It was only after a while that they realised that there is actually a large landmass there under the ice - one bigger than Australia. The name Antarctica was made for this new seventh continent. So now the world had seven continents.

Back to Six

Some people feel that the distinction between continents should be a physical one. The distinction between Europe and Asia is purely historical, based on a lack of knowledge by the earliest Greeks, so why separate Europe and Asia into two? These people invented the name Eurasia for this new supercontinent, the biggest in the world.

Plate Tectonics

In the mid 20th century it was discovered that the landmasses of the world are not fixed. They are plates of rock floating on the semi-liquid magma underneath, and they slide around. North and South America are moving west away from Europe and Africa. Australia and India are part of the same mass, even though they are separated by sea, and are moving northwards. The collision of India with the rest of Asia is forming the Himalaya mountains, which are continuing to get taller.

While most continents correspond roughly with tectonic plates, there are some anomalies - Greece is in Europe but is on a separate plate. India, as already mentioned, is part of Australia. And Europe and Asia are one continent.

So What About Oceania and Australasia?