A island It is a land mass that is surrounded by water on all sides. To be an island, the land portion must, by definition, be smaller than a continent.
In general, the islands originate due to the movement of tectonic plates . These earth blocks are in constant interaction with each other, and this can lead to the formation of islands.
In addition, the shocks and separations of the tectonic plates, the islands can also be formed as a result 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.
Index
- 1 Characteristics of the Islands
- 2 Types of Islands
- 3 References
Characteristics of the Islands
To be considered islands, these portions of land must have certain characteristics. Here 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 has more than 2 million square kilometers of extension.
- They must be separated from a continent for 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, you can see a relatively similar climate at that level.
- The smaller islands are called islets. Generally they are depopulated zones, but they count on their respective fauna and flora.
- A set 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.
Types of Islands
Depending on the geological phenomenon that gives rise to the islands, they are classified into different types. Briefly, we will describe the most representative types of islands:
Continental islands
These types of islands are linked to the continental shelf. They are far from the continent due to the rise in sea level just in the section that separates the island from the continent.
The continental islands are extensions of the continents. This is known thanks to the existence of geological evidence and fossils who verify it. Greenland is an example of a continental 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, the oceanic islands can be of two types:
- Volcanic islands : they 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 earth 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 mouths of rivers. These sediments are carried away by the current of the river, and later deposited along its path, giving rise to the formation of the deltas
River Islands
This type of islands is formed by the accumulation of particles in the central channel of some rivers.
References
- Definition of Island (s.f.). Dictionary Definition ABC. San Salvador, El Salvador. Retrieved from: definicionabc.com
- Islands - Characteristics. GeoEnciclopedia. Retrieved from: geoenciclopedia.com
- Islands: oceanic, continental, volcanic, coral (s.f.). Retrieved from: astromia.com
- Pérez, J., and Merino, M. (2009). Definition of Island. Retrieved from: definicion.de
- Wikipedia, The Free Encyclopedia (2017). Island. Retrieved from: en.wikipedia.org