Plate Tectonics Practice Test 2025 – All-in-One Guide to Mastering Your Exam!

Oceanic plates subduct beneath continental plates during convergence due to their relative densities. Oceanic plates are generally composed of basalt and are denser compared to the continental plates, which are primarily made of lighter granitic rocks. The higher density of the oceanic plate causes it to sink or subduct beneath the continental plate, which is more buoyant. This process leads to the formation of deep ocean trenches and is a fundamental aspect of plate tectonics.

The concept of density is crucial in understanding this phenomenon. In a collision scenario, the denser oceanic plate is forced down into the mantle beneath the less dense continental plate, leading to subduction. This process also results in geological features such as volcanic arcs and earthquakes, which are associated with the dynamics of subduction zones.

The other options do not accurately reflect the principles of plate tectonics. For instance, the idea that oceanic plates are lighter contradicts the fundamental understanding of density and buoyancy, while the assertion about the thickness of plates does not directly relate to why subduction occurs in this context. Subduction relies primarily on the differences in density rather than thickness or other attributes.