Polygon Island

An island may be described as such despite the presence of an artificial land bridge, for example Singapore and its causeway, or the various Dutch delta islands, such as IJsselmonde. Some places may even retain “island” in their names for historical reasons after being connected to a larger landmass by a wide land bridge, such as Coney Island or Coronado Island.

The world’s largest island, Greenland, with an area of over 2.1 million km2, while Australia, the world’s smallest continent has an area of 7.6 million km2, but there is no standard of size which distinguishes islands from continents, or from islets. There is a difference between islands and continents in terms of geology. Continents sit on continental lithosphere which is part of tectonic plates floating high on Earth’s molten mantle.

Difference between islands and continents in terms of geology. Continents sit on continental lithosphere which is part of tectonic plates floating high on Earth’s molten mantle. Oceanic crust is also part of tectonic plates, but it is denser than continental lithosphere, so it floats low on the mantle. Islands are either extensions of the oceanic crust (e.g. volcanic islands) or geologically they are part of some continent sitting on continental lithosphere (e.g. Greenland).