The Number of Continents on Earth Is More Complicated Than You Think

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A continent is typically defined as a very large landmass, surrounded on all sides (or nearly so) by water, and containing a number of nation-states. However, when it comes to the number of continents on earth, experts don't always agree. Depending on the criteria used, there may be five, six, or seven continents. Sounds confusing, right? Here's how it all sorts out.

Defining a Continent

The "Glossary of Geology," which is published by the American Geosciences Institute, defines a continent as “one of the Earth’s major land masses, including both dry land and continental shelves." Other characteristics of a continent include:

  • Areas of land that are elevated in relation to the surrounding ocean floor
  • A variety of rock formations, including  igneous, metamorphic, and sedimentary 
  • A crust that is thicker than those of the surrounding oceanic crusts. For example, the continental crust may vary in thickness from about 18 to 28 miles in depth, whereas oceanic crust is usually about 4 miles thick. 
  • Clearly defined boundaries

This last characteristic is the least well defined, according to the Geological Society of America, leading to confusion among experts as to how many continents there are. What's more, there is no global governing body that has established a consensus definition.

How Many Continents Are There?

Using the criteria defined above, many geologists say there are six continents: Africa, Antarctica, Australia, North and South America, and Eurasia. If you went to school in the United States, chances are you were taught that there are seven continents: Africa, Antarctica, Asia, Australia, Europe, North America, and South America.

In many parts of Europe, however, students are taught that there are only six continents, and teachers count North and South America as one continent.

Why the difference? From a geological perspective, Europe and Asia are one large landmass. Dividing them into two separate continents is more of a geopolitical consideration because Russia occupies so much of the Asian continent and historically has been politically isolated from the powers of Western Europe, such as Great Britain, Germany, and France.

Recently, some geologists have begun arguing that room should be made for a "new" continent called Zealandia. According to this theory, this landmass lies off the eastern coast of Australia. New Zealand and a few minor islands are the only peaks above water; the remaining 94 percent is submerged beneath the Pacific Ocean.

Other Ways to Count Landmasses

Geographers divide the planet into regions, and generally not continents, for ease of study. The Official Listing of Countries by Region divides the world into eight regions: Asia, the Middle East and North Africa, Europe, North America, Central America and the Caribbean, South America, Africa, and Australia and Oceania.

You can also divide the earth's major landmasses into tectonic plates, which are large slabs of solid rock. These slabs consist of both continental and oceanic crusts and are separated by fault lines. There are 15 tectonic plates in total, seven of which are roughly 10 million square miles or more in size. Not surprisingly, these roughly correspond to the shape of the continents that lie atop them.

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Rosenberg, Matt. "The Number of Continents on Earth Is More Complicated Than You Think." ThoughtCo, Dec. 3, 2017, thoughtco.com/six-or-seven-continents-on-earth-1435100. Rosenberg, Matt. (2017, December 3). The Number of Continents on Earth Is More Complicated Than You Think. Retrieved from https://www.thoughtco.com/six-or-seven-continents-on-earth-1435100 Rosenberg, Matt. "The Number of Continents on Earth Is More Complicated Than You Think." ThoughtCo. https://www.thoughtco.com/six-or-seven-continents-on-earth-1435100 (accessed December 12, 2017).