Major Islands and Archipelagos of the World: GK Notes

An island is a piece of land smaller than a continent and surrounded by water on all sides; a group of islands lying together is an archipelago. Geography papers return to this topic because it carries easy marks of a very particular kind: which island is the largest, which country owns which group, which channel runs between two islands, and which island belongs to which sea. This note sets out the types of islands, the largest islands of the world, the great archipelagos, the island possessions of India, and the channels that examiners pair with them.

How islands are formed

Continental islands are fragments of a continental shelf cut off by a rise in sea level or by the drifting apart of land masses; Greenland, Madagascar, Great Britain and Sri Lanka are of this kind. Oceanic or volcanic islands rise from the ocean floor where a hot spot or a plate margin pushes lava above the surface; Hawaii, Iceland, the Azores and Barren Island in the Bay of Bengal belong here. Coral islands are built by the skeletons of coral polyps in warm shallow water and take the form of atolls, as in the Maldives and in Lakshadweep. Barrier islands are long sandy ridges thrown up parallel to a coast, Sriharikota in Andhra Pradesh being the Indian example. River islands are made of silt deposited by a river in its own channel, of which Majuli in the Brahmaputra is the largest. Tidal islands are joined to the mainland at low water, and artificial islands are reclaimed by human effort.

The largest islands of the world

Greenland is the largest island on earth. Australia is larger still, but it is counted a continent and not an island, which is the commonest trap set on this list. Among islands shared between countries, Borneo is divided between three, Indonesia, Malaysia and Brunei; New Guinea between Indonesia and Papua New Guinea; Hispaniola between Haiti and the Dominican Republic; Tierra del Fuego between Chile and Argentina; and Ireland between the Republic of Ireland and the United Kingdom. Java carries more people than any other island in the world, Honshu is the largest island of Japan and Luzon of the Philippines, Baffin Island is the largest of Canada, Sicily the largest in the Mediterranean and Cuba the largest in the Caribbean.

The great archipelagos

Indonesia is the largest archipelago in the world, a chain of more than seventeen thousand islands of which Java, Sumatra, Sulawesi and the Indonesian part of Borneo and New Guinea are the chief; with the Philippines and the neighbouring groups it forms the Malay Archipelago. The Japanese archipelago runs north to south as Hokkaido, Honshu, Shikoku and Kyushu. The Hawaiian Islands are a volcanic chain in the mid Pacific built over a hot spot, and the Aleutian Islands curve from Alaska towards Asia along a plate margin. The Galapagos Islands, which Charles Darwin studied, belong to Ecuador; the Canary Islands belong to Spain and the Azores to Portugal. The British Isles, the Greek islands of the Aegean, the Maldives, the Seychelles, the Bahamas and Svalbard in the Arctic complete the list a paper setter draws from.

The islands of India and their channels

India has two island groups and a scatter of coastal and river islands. The Andaman and Nicobar Islands lie in the Bay of Bengal and are the summits of a submerged mountain chain; their capital is Port Blair, their highest point is Saddle Peak in North Andaman, Barren Island is the only active volcano in India, and Indira Point in Great Nicobar is the southernmost point of the country. Lakshadweep lies in the Arabian Sea and is made entirely of coral atolls and reefs, with Kavaratti as its capital and Minicoy as its southernmost inhabited island. The channels are asked as often as the islands: the Ten Degree Channel separates the Andaman group from the Nicobar group, the Coco Channel separates the Andamans from the Coco Islands of Myanmar, Duncan Passage lies between South Andaman and Little Andaman, the Nine Degree Channel separates Minicoy from the rest of Lakshadweep and the Eight Degree Channel separates Minicoy from the Maldives. Elsewhere, Majuli in the Brahmaputra is the largest river island, Sriharikota is a barrier island carrying the launch centre of the Indian space programme, Rameswaram or Pamban Island faces Sri Lanka across the Palk Strait and the Gulf of Mannar, and Sagar Island lies in the Ganga delta.