What is an island

what is an island

When we talk about the different existing geological forms, we see that the islands are one of the most attractive from a tourist point of view. And is that the islands keep unique characteristics and ecosystems really worth knowing. However, not everyone knows exactly what is an island. They harbor geological characteristics and certain conditions must be met to do so.

In this article we are going to tell you what an island is, what its characteristics and its origin are.

What is an island

types of islands

An island is a land completely surrounded by water, which is smaller than the mainland. When several islands are close together, they are collectively called an archipelago.

There are several types of islands according to their appearance, and their different sizes and shapes. The largest are Greenland, Madagascar, New Guinea, Borneo, Sumatra and Baffin Island, while the smallest are infinitely more numerous because they are not only scattered in the middle of the ocean, but also in lakes and even rivers. These islands are usually small pieces of land, usually without human life, but with plants and other animals.

The smaller islands are called islets, usually without humans, but with plants and animals. The islands are frequently associated with the concept of paradise. They are also related to loneliness and the existence of a virgin life. They have been quite important to human populations. Many of the countries are settled on one or more islands and can have a fairly high economic relevance as is the case of Japan. Japan is a nation installed in some islands of the Pacific Ocean and today stands out for its art and economy. The technological advances of Japan has developed without any problem despite developing the country into an island.

To know in depth what an island is, we are going to see more or less the definition that is given according to the Millennium Systems Assessment. These are isolated lands surrounded by water, populated and separated from a continent by at least 2 kilometers. Its size must be equal to or greater than 0.15 kilometers. It must be borne in mind that many islands are full sites full of biodiversity and endemic species. An endemic species is one that is exclusive to an ecosystem and that cannot exist in another place since it needs these conditions in order to survive. For example, the lemur is an animal that is only found on Madagascar, an island.

What is an island: formation

what is an island and its characteristics

Once we know what an island is, we will try to explain their formation. The islands have existed because the plate tectonics of our planet is in constant motion. We remember that planet Earth has numerous boxes that are made up of different materials. The Earth's mantle is composed of currents of convection due to difference in density of materials and this causes the continental crust to shift. This crust is made up of tectonic plates and they drift continuously over time.

The islands also move with the tectonic plates. Sometimes they come together and other times they separate. Therefore, they can appear over the course of many millions of years as a result of geological events such as a volcanic eruption of a marine volcano. There are several ways in which an island can be formed and from this they are placed in different types.

Types of islands

paradise zone

There are different types of islands according to their characteristics. These islands are divided into two main types which are continental and oceanic. Let's see what the characteristics of each of them are:

  • Continental islands: They belong to the continental shelf. Many were part of the continent, but were isolated after sea level rise. This type is the so-called "tidal island", which occurs when high tide covers the part of the land that connects one area to another. Therefore, part of it is surrounded by water. Barrier islands consist of land parts parallel to the coast, many of which are part of the continental shelf. They can be the result of ocean currents pushing sand and sediment, or even melting materials in the last ice age that caused sea level rise. Examples of this type of islands are Greenland and Madagascar.
  • Oceanic islands: They are not part of the continental shelf. Some are also called volcanic islands because they are formed by any type of underwater volcanic eruption. Oceanic islands are usually located in subduction zones where one plate sinks below another, although they can also form over hot spots. In this case, the plate moves above that point, as the magma moves upward, causing the earth's crust to rise.

Other oceanic islands arose from the movement of tectonic plates as they rose above sea level. Sometimes large groups of coral form huge coral reefs. When the calcium bones of these animals (composed mainly of calcium carbonate) pile up so disproportionately that they appear above sea level, they form an island of coral. Of course, other materials are added to the bones.

If bones accumulate around oceanic islands (usually volcanoes), over time, the ground in the center sinks and becomes covered with water to form a lagoon, the result is an atoll. An example of this type of island is the Hawaiian Islands and the Maldives.

Artificial islands

The human being has managed to create artificial islands based on modern technology. Platforms made with metallic materials and cements can serve as a simulator of a continental shelf. However, the essence of an island will never be the same even if the human being tries to imitate it.

As you can see, the islands are quite interesting from a geological and biological point of view. I hope that with this information you can learn more about what an island is and what its characteristics are.


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