How do islands form?
Most islands are formed naturally. This can happen through underwater volcanic eruptions. As volcanoes erupt, the volcanic material builds up and can eventually rise above the ocean creating an island.
Islands can also be formed when tectonic plates move. Tectonic plates are huge pieces of rock that lie under the Earth's crust. When tectonic plates that are in the middle of the ocean move, they can push land up that was underwater, giving rise to an island. Islands can also be created by using machines that force sand to the top of the ocean instead of the bottom.
Coral islands are a type of island made from the skeletons of coral that build up over time to create coral reefs.
Types of islands
There are two main types of islands: continental islands and oceanic islands. Some islands are artificial like the Kansai airport in Japan which sits on a man-made island.
Continental islands sit on top of a continental shelf. A continental shelf is the part of the continent that is under water. Great Britain, for example, is connected to the continental shelf of Europe.
Oceanic islands are islands that do not sit on a continental shelf. Many oceanic islands are formed by undersea volcanoes like Hawaii.
Did you know?
- The size of islands is constantly changing due to tides of the ocean.
