Category Social Sciences

Artificial islands are man-made islands. Such islands have been created by expanding existing islets which are very tiny islands. This can be done by draining the water around an islet, so as to create more land.

Artificial islands can also be built by construction on existing reefs, or by joining together several natural islets into a bigger island. Thus, they vary widely in size, from tiny islets that have been created to hold just a single pillar, building, or other structure, to those that support entire communities.

Artificial islands can also be created from material brought in from elsewhere. Dubai’s huge artificial islands are shaped like palm trees, and a map of the world.

Artificial islands are not a new concept. Even in the 14th century, the Nahua people created their capital, Tenochtitlan, on an artificial island in Lake Texcoco. Today, Mexico City sits on the remains of this ancient capital. 

Barrier islands are long, thin, and sandy islands that run parallel to the coast. Between a barrier island and the main-land, there will be a calm, protected body of water such as a lagoon or bay.

In order for barrier islands to form, several conditions must be met. First, there must be a source of sand to build the island. Next, the coastline must have a broad, gentle slope. Finally, the forces of waves, tides, and currents must be strong enough to move the sand, so as to form an island.

Once formed, barrier islands are dynamic. The winds and waves constantly rework, and move the barrier island sand. Changes in sea level also affect these islands. Each barrier island has a shoreline that faces the open sea, and receives the full force of waves. This shoreline is often called the beach. Behind the beach, there will be sand dunes.

Coral islands are special, because they are made up of the skeletons of living creatures called coral polyps.

Millions of these tiny animals build tough shell-like homes, one on top of another, to form a reef. If the sea bed rises, or the sea level falls even slightly, these reefs are left above the sea as islands.

A coral island is, therefore, a part of a coral reef. Coral islands are sometimes shaped like rings, and consist of low land, perhaps only a few metres above sea level, generally with coconut palms and surrounded by white coral sand beaches.

Most of the world’s coral islands are found in the Pacific Ocean and some in the Indian Ocean. One such coral island is Maldives. 

 Islands can be formed by volcanic activity under the sea. Over millions of years, lava erupting from the sea floor builds up.

The lava cools rapidly as it comes in contact with the water, and forms solid rock. Each eruption from the sea floor builds up the solid rock higher and higher to form an undersea volcanic mountain. Finally, the mountain becomes so tall that it rises above the ocean’s surface to create a volcanic island.

Mauna Loa is one of five volcanoes that form the Island of Hawaii. It is the most massive single mountain in the world, because of its sheer bulk.

 Mauna Loa has been erupting for at least 700,000 years, and may have emerged above sea level about 400,000 years ago. The volcano’s magma comes from the Hawaii hot-spot, which has been responsible for the creation of the Hawaiian island chain over tens of millions of years. 

Continental islands lie off the large land masses that form continents. They lie on the continental shelf, which is the sloping, underwater ledge found at the edge of continents.

Continental islands were once part of a huge single land mass called Pangaea. Eventually, slow movements of the Earth’s crust broke Pangaea apart into several pieces that began to drift away. When the breakup occurred, some large chunks of land split from the bigger land masses. These fragments of land that were surrounded by the sea became islands.

Greenland and Madagascar are examples of continental islands that were formed in this manner. Other continental islands were formed because of changes in the sea level.

About 18,000 years ago, ice covered large parts of our planet. As this ice began to melt, the sea level rose. The ocean flooded many low-lying areas, creating islands such as the British Isles, which were once part of mainland Europe.