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 isn’t just one perfect way 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 itself, 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 originally described any large, connected area of land, not just the huge ones we think of today. Even small places like the Isle of Man, Ireland, and Wales were once called continents.

Over time, people began to use the word for the world's biggest land areas. Writers like Peter Heylin and Ephraim Chambers helped shape this idea, talking about continents as huge, connected lands. Today, we usually 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 sense. 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 are 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

In addition to the continents we know today, there have been huge landmasses called supercontinents in the past. These were big pieces of Earth's crust that have since broken apart and moved to form the continents we see now. Examples include Vaalbara, Kenorland, Columbia, Rodinia, Pannotia, and Pangaea.

Some large parts of continents are called subcontinents. These are big areas that are separated from the rest of the continent. The most famous example is the Indian subcontinent. Other examples might include the Arabian Peninsula, Southern Africa, the Southern Cone of South America, and Alaska. Sometimes, Greenland is also called a subcontinent because it sits on its own tectonic plate.

There are also areas of land called submerged continents that are mostly under the ocean. One example is Zealandia, which is mostly under the ocean but rises above it in New Zealand and New Caledonia. Another is the Kerguelen Plateau in the southern Indian Ocean.

Geologists define a continent using four main ideas: it should be higher than the ocean floor, made of certain types of rock, have a thicker crust, 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 the Greek word for a large landmass. Ancient Greek sailors first named Europe and Asia after the lands on either side of waterways like the Aegean Sea and the Black Sea. They weren’t sure whether Africa should be its own continent or part of Asia. Over time, people generally agreed on three continents: Europe, Asia, and Africa.

When Europeans began 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 realized the Americas were a separate landmass big enough to be called its own continent. Maps began showing North and South America as separate from Asia. Later, people discovered Australia and Antarctica, adding to the list of 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 special thick rock called continental crust. This crust is made of metamorphic and igneous rocks, often containing granitic material. Because it is less dense than the oceanic crust below, it floats higher, forming the land we see above sea level.

Geologists sometimes talk about stable parts of continents called cratons, which have not changed much since very old times. These cratons have ancient rocks and are surrounded by layers of younger rock. Continents can grow by adding volcanic islands and smaller land pieces, especially along their active edges. Some smaller land areas, like Zealandia, are considered microcontinents because they are made of the same thick rock as bigger continents.

Criticism

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