Which process describes the collision of continental and oceanic plates with the oceanic plate descending into the mantle?

• A. Subduction
• B. Spreading
• C. Rift
• D. Accretion

Answer: (A)

Subduction describes what happens when an oceanic plate meets a continental plate and the heavier oceanic slab sinks into the mantle beneath the overriding continental plate. The sinking is driven by density differences, with the cooler, more dense oceanic crust descending as the plates collide. This descent forms a deep trench, triggers strong earthquakes, and causes melting in the overlying mantle due to fluids released from the subducting slab. The generated magma rises to form volcanic arcs along the continent. Spreading involves plates moving apart and creating new crust at mid-ocean ridges, not a plate descending beneath another. Rift is a pulling-apart process, often within a continent, and accretion refers to material adding to a landmass, not the sinking of a plate. Subduction is the correct description of the scenario.