Science Olympiad Dynamic Planet Practice Test 2026 – Your Comprehensive Guide to Success!

When one oceanic plate is subducted beneath another, an island arc is formed as a result of the subduction process. This occurs because the descending oceanic plate goes into the mantle where it melts due to the extreme heat and pressure. The melting of the subducted plate generates magma, which is less dense than the surrounding solid rock and rises to the surface. As this magma erupts, volcanic islands are created along a curved belt typically parallel to the subduction zone.

These island arcs often consist of a series of volcanoes that create a unique landform characteristic of oceanic-oceanic convergent boundaries, where two oceanic plates collide. Examples include the Aleutian Islands in Alaska and the Japanese archipelago.

In contrast, a continental shelf is a submerged landform that borders the continents, a mid-ocean ridge is a feature that forms at divergent boundaries where tectonic plates move apart, and a volcanic dome is created from lava that is highly viscous, making it pile up close to the vent rather than flow away. None of these features arise from the direct subduction of one oceanic plate beneath another.