WHAT IS AN ISLAND? CHARACTERISTICS AND TYPES - GEOGRAPHY - 2025

An island is a land mass that is surrounded by water on all sides. To be an island, the piece of land must, by definition, be smaller than a continent.

In general, islands originate due to the movement of tectonic plates. These blocks of land are in constant interaction with each other, and this can generate the formation of islands.

In addition to the collisions and separations of the tectonic plates, islands can also be formed as a consequence of a geological event, such as a strong volcanic eruption.

Likewise, the joint action of erosion and sedimentation also gives rise to the formation and permanence of the islands.

Characteristics of the Islands

To be considered islands, these portions of land must have certain characteristics. Below are some particularities of the islands, from the geological point of view:

- They must have a minimum length of 150 meters.

- The size of the islands is extremely varied. The largest island is Greenland, and it is more than 2 million square kilometers in size.

- They must be separated from a continent by 2 kilometers or more.

- They can be located in the open sea, rivers and lakes, with very different shapes and sizes.

- If the climate is evaluated in the areas that are at the same height above sea level, a relatively similar climate can be seen at said elevation.

- The smaller islands are called islets. They are generally unpopulated areas, but they have their respective fauna and flora.

- A group of islands close to each other is known as an archipelago.

- Many islands have animals and plants native to that sector. For example: the Lemur of Madagascar is a native of that island.

Island Types

Depending on the geological phenomenon that gives rise to the islands, they are classified into different types. We will briefly describe the most representative types of islands:

Continental islands

These types of islands are attached to the continental shelf. They are far from the mainland due to rising sea levels right in the section that separates the island from the mainland.

The continental islands are extensions of the continents. This is known thanks to the existence of geological evidence and fossils that confirm it. Greenland is an example of a mainland island.

Oceanic islands

Unlike the continental islands, these land masses are not part of the continental shelf. In contrast, its origin is due to other geological phenomena such as the interaction of tectonic plates, for example.

In turn, oceanic islands can be of two types:

- Volcanic islands: originate from the eruption of an underwater volcano. This geological activity induces a strong movement of the tectonic plates that induces the movement of the land mass.

- Coral islands: they are located in tropical seas and are formed based on the calcareous skeletons of corals.

Sedimentary islands

They are formed due to the accumulation of sand, mud and / or gravel at the mouth of rivers. These sediments are dragged by the current of the river, and later deposited along its route, giving rise to the formation of deltas

River islands

This type of islands is constituted thanks to the accumulation of particles in the central channel of some rivers.

References

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2. Islands - Characteristics. GeoEncyclopedia. Recovered from: geoenciclopedia.com
3. Islands: oceanic, continental, volcanic, coral (sf). Recovered from: astromia.com
4. Pérez, J., and Merino, M. (2009). Definition of Island. Recovered from: definicion.de
5. Wikipedia, The Free Encyclopedia (2017). Isla. Recovered from: es.wikipedia.org