An archipelago is a specific geological land formation that is made up of a number of islands. It is sometimes referred to as an island chain or island cluster. The various islands that are considered part of the same archipelago are located relatively close together. These formations are most commonly found in saltwater environments, like oceans and seas. The area of each of the islands within an archipelago varies; some islands are quite insignificant in size, while others may cover a large area.
How Is an Archipelago Formed?
The typical cluster or chain formation of an archipelago could be the result of several geological activities, including volcanic activity, erosion, and flooding.
The majority of archipelagos located in oceans are believed to be the result of volcanic activity. These landforms begin to take shape when underwater volcanoes erupt and release hot lava into the ocean. As the lava cools off, it turns into solid rock. This rock continues to grow over time with subsequent eruptions until eventually, it protrudes through the surface of the ocean. This volcanic growth forms the beginning of an island. The lava continues to accumulate and spread out over the surface of the ocean until the island reaches a significant size and in many cases begins to support living organisms. Volcanic archipelagos take shape either as the result of several volcanoes being located in close proximity (each erupting and forming different islands) or that a single volcano shifts its position over the ocean floor due to tectonic plate activity (creating new islands as it moves).
The second likely cause of island chain formation is that erosion wears away at a larger landmass, creating small islands over an extended period time. As the tide moves in and out, it carries away sediment. Although not very common, this repetitive action can cause small areas of the larger landmass to break away, taking on an island shape. In a similar manner, deposits of eroded sediment may also collect in one particular location, becoming an island after a certain amount of time. Additionally, plate tectonic activity may cause land to break away and form islands.
Flooding may also cause archipelagos to form. Researchers have discovered, for example, that some islands appeared after the previous ice age had ended. These relatively new formations were the result of glaciers melting. Water from the melting glaciers caused the sea levels to rise, flooding valleys located close to the shores of major landmasses. Consequently, what were once mountain peaks are now considered islands.
Types of Archipelagos
All archipelagos consist of a chain or group of several freestanding islands. These landforms, however, can be categorized into different types: continental fragments, continental islands, and oceanic islands. Each distinction is based on how the islands were formed.
A continental fragment occurs when plate tectonic activity causes land to break away from a continental landmass. The resulting islands may occur hundreds of miles from the shore of the original landmass. Some theories suggest that the islands in eastern Indonesia (an archipelago) were formed as a result of continental fragmentation.
The term “continental island” is used to describe any island that is located within the continental shelf area of a particular continent. One example of a continental island archipelago is the Kerguelen Islands, which are located in the southern region of the Indian Ocean.
Archipelagos made up of oceanic islands are landforms that are not located within a continental shelf area. These islands are almost always of volcanic origin and can occur in several locations, including volcanic hotspots, volcanic island arcs, where oceanic rifts come to the surface of the ocean. Hawaii, the Aleutian Islands, the Lesser Antilles are all considered oceanic island archipelagos.
Largest Archipelago in the World by Area
The largest archipelago in the world, as measured by total area, is the Malay archipelago. The Malay archipelago is surrounded by the Indian and the Pacific Oceans to the east and west and Indochina and Australia to the north and south. It covers an area of approximately 770,000 square miles and is made up of more than 25,000 individual islands. When discussing international trade concerning marine transportation, it is often referred to as Maritime Southeast Asia. This entire region sits within a tropical climate zone.
In addition to being the largest archipelago area in the world, it also displays some of the highest rates of volcanic activity. This activity has resulted in a varied landscape, characterized by tall mountain peaks. Some of the major, smaller archipelagos located within this mega-archipelago include Indonesia, New Guinea (although some researchers do not consider this part of the Malay Archipelago), and the Philippine archipelago.
Of these subregions, Indonesia is the largest by area, population, and number of islands. In fact, Indonesia makes up most of the larger Malay Archipelago. It covers 735,358 square miles and has a population size of over 261 million individuals. Although the number of islands within Indonesia is not known exactly, the most recent estimates suggest it is comprised of more than 18,000 islands. Over 14,000 of these have been registered with official names at the UN Conference on the Standardization of Geographical Names. Of the islands that make up Indonesia, Sumatra is the largest by area. It covers 182,812 square miles and is situated from northeast to southwest. Despite its size, Sumatra is not the most populated island in Indonesia. That distinction is given to the island of Java.
Importance of Archipelagos
Archipelagos are some of the most important geological land formations in the world. They provide additional waterways through which to transport goods around the world. The islands making up archipelagos also increase the available land area for human populations. Where governed by the UN Convention on the Law of the Seas, archipelagos may increase territorial waters of certain countries, which is an important step in protecting their economic interests.
Additionally, archipelagos create unique marine habitats that host a diverse range of plant and animal species both off the shore and on the land. Many types of scientists (like biologists, geologists, and geographers) value archipelago land formations. These features are important to a number of research projects because they provide clues about the processes of ecological and geographical evolution.
About the Author
Amber is a freelance writer, English as a foreign language teacher, and Spanish-English translator. She lives with her husband and 3 cats.
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