Continent

A continent is one of the large land areas that make up Earth. People usually agree on what counts as a continent, but there are different ways to decide. A continent can be a huge piece of land all by itself, like Africa, or it can include nearby islands, like how many islands in the Pacific Ocean are grouped with Australia to form Oceania. Because of these different ways to look at it, some people say there are seven continents, while others say there are only four.

Most people who speak English think of seven continents. From biggest to smallest, they are Asia, Africa, North America, South America, Antarctica, Europe, and Australia. But sometimes people combine some of these. For example, they might call Asia and Europe together “Eurasia,” or they might call North America and South America the Americas.

Scientists who study the Earth, called geologists, have their own way of thinking about continents. To them, a continent is a big part of Earth’s crust that sits on a moving piece called a tectonic plate. These big pieces of crust broke apart from one huge supercontinent called Pangaea many millions of years ago, and that’s why we have the continents we see today.

Etymology

The word "continent" comes from old English and Latin words meaning "connected land." It used to describe any large area of land that was connected. Even small places like the Isle of Man, Ireland, and Wales were once called continents.

Now, people use the word for the world's biggest land areas. Writers like Peter Heylin and Ephraim Chambers helped change this idea. Today, we think of continents as the major landmasses like Europe, Asia, and Africa.

Definitions and application

A continent is a large area of land, usually separated by water. All continents are islands in this way. For example, Greenland is the world's largest island, but Australia is the smallest continent because it is much bigger.

Earth's main land areas all touch one big ocean, the World Ocean. Geologists define a continent by four main features: it sits higher than the ocean floor, has many types of rocks, has a thicker crust than the ocean floor, and covers a large enough area.

The idea of a continent can change. Sometimes it means just the dry land, like when we talk about continental Europe, which means mainland Europe without islands such as Great Britain or Ireland. Other times, it includes nearby underwater areas and islands that are part of the same land, like how Great Britain is part of Europe even though it is an island.

Main article: Boundaries between the continents

See also: List of transcontinental countries

Sometimes, continents are not completely separated by water. For example, Africa and Asia are connected by a narrow strip of land called the Isthmus of Suez. North and South America are also connected by a narrow strip called the Isthmus of Panama. Even though they are joined, we often think of them as separate continents.

There are different ways to count continents. Most English-speaking countries teach that there are seven continents. Some places teach that there are six continents by combining America into one or Eurasia into one. Zealandia, a submerged land area, is sometimes called the eighth continent.

Area and population

For a more detailed list of populations by continental regions and subregions, see List of continents and continental subregions by population.

The table below shows the size and population of each continent. The sizes come from the Encyclopædia Britannica and use the seven-continent model. This model includes Australasia, Melanesia, Micronesia, and Polynesia as part of Oceania. The populations are estimates from 2021 by the United Nations Statistics Division, following the United Nations geoscheme. This includes all of Egypt (with the Isthmus of Suez and the Sinai Peninsula) as part of Africa. It also includes Armenia, Azerbaijan, Cyprus, Georgia, Indonesia (including Western New Guinea), Kazakhstan, and Turkey (including East Thrace) as parts of Asia. Russia (including Siberia) is considered part of Europe. Panama and the United States (including Hawaii) are parts of North America, and Chile (including Easter Island) is part of South America.

Other divisions

Main article: Supercontinent

Further information: Geological history of Earth

Besides the continents we have today, there have been huge landmasses called supercontinents long ago. These were large parts of Earth's surface that later split apart and moved to become the continents we know now. Examples are Vaalbara, Kenorland, Columbia, Rodinia, Pannotia, and Pangaea.

Some big parts of continents are called subcontinents. These are large areas separated from the rest of the continent. The best known is the Indian subcontinent. Others include the Arabian Peninsula, Southern Africa, the Southern Cone of South America, and Alaska. Sometimes, Greenland is called a subcontinent because it sits on its own tectonic plate.

There are also land areas called submerged continents that lie mostly under the ocean. One example is Zealandia, which is mainly under water but comes up in New Zealand and New Caledonia. Another is the Kerguelen Plateau in the southern Indian Ocean.

Scientists use four main ideas to decide what is a continent: it should be higher than the ocean floor, made of certain rocks, have a thicker surface layer, and be larger than one million square kilometres. With Zealandia added in 2017, there are now seven geological continents: Africa, Antarctica, Australia, Eurasia, North America, South America, and Zealandia.

History of the concept

The word "continent" comes from an old Greek word for a big piece of land. Long ago, sailors from Greece named Europe and Asia after the lands next to seas like the Aegean Sea and the Black Sea. They weren’t sure if Africa was its own continent or part of Asia. Over time, most people agreed on three continents: Europe, Asia, and Africa.

When Europeans started exploring the Americas in the late 1400s, they weren’t sure if they had found a new continent or just part of Asia. By the early 1500s, some explorers saw that the Americas were big enough to be a separate continent. Maps then showed North America and South America as separate from Asia. Later, people found Australia and Antarctica, adding more continents. Today, most people think of seven continents: Europe, Asia, Africa, North America, South America, Australia, and Antarctica. Some people group Europe and Asia together as Eurasia, which would make six continents.

Geology

In geology, a continent is made of thick rock called continental crust. This crust is made of special rocks and often has granitic material. Because it is lighter than the rock below, it floats higher, forming the land we see above sea level.

Geologists talk about stable parts of continents called cratons. These cratons have very old rocks and are surrounded by younger rock layers. Continents can grow by adding volcanic islands and smaller land pieces, especially along their edges. Some smaller land areas, like Zealandia, are called microcontinents because they are made of the same thick rock as bigger continents.

Criticism

Some scholars think that how we see continents is shaped more by history, culture, and politics than by the land and rocks themselves. This idea is explored in a book called The Myth of Continents: A Critique of Metageography by Martin W. Lewis.