Category Geography

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.

While an island is surrounded by water on all sides, a peninsula is bordered by water only on three sides. A peninsula will always be connected to the mainland on one side. Peninsulas can be small, or very large. They are found on every continent.

In Europe, Portugal and Spain form the Iberian Peninsula. The Horn of Africa, which juts into the Arabian Sea, is a huge peninsula. The nations of North Korea and South Korea make up the Korean Peninsula in Eastern Asia.

 In Australia, there is the Cape York Peninsula. And of course, the Indian subcontinent forms a huge peninsula, bordered by the Arabian Sea, the Bay of Bengal, and the Indian Ocean.

Sometimes, islands are formed very close together, in clusters. Such a cluster of islands is called an archipelago.

Archipelagos can be made up of hundreds, or even thousands, of islands. These islands may differ from one another in their plant and animal life.

 Japan, Indonesia, the Philippines, New Zealand, Greece, Hawaii, Maldives, Azores, and New York City are examples of well-known archipelagos. Indonesia is the world’s largest archipelago by area and population.

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