Question

Explain how ocean ridges and trenches are formed.

Answer 1

Ocean ridges are formed through a process called seafloor spreading, where magma rises up from the Earth's mantle and spreads out, pushing the existing seafloor apart. The magma then cools and solidifies, forming new seafloor. Over time, this continuous process creates a long, elevated mountain range on the ocean floor, known as an ocean ridge.

On the other hand, ocean trenches are formed through subduction, which occurs when a tectonic plate carrying oceanic crust collides with a plate carrying continental crust or another tectonic plate. The heavier, denser oceanic crust is forced to sink below the lighter continental or other oceanic crust, causing it to form a deep cleft in the ocean floor known as a trench. The subducting plate is heated and dehydrated as it descends, releasing magma that rises to the surface and forms volcanic islands or arcs. Over time, this process can lead to the formation of a chain of trenches and volcanic arcs, known as a subduction zone.