Science Olympiad Dynamic Planet Practice Test

What causes the formation of new oceanic crust?

1. Subduction of continental plates

2. Cooling of mantle material at mid-ocean ridges

3. Destruction of older oceanic crust

4. Weathering of surface rocks

The correct answer is: Cooling of mantle material at mid-ocean ridges

The formation of new oceanic crust primarily occurs through the cooling of mantle material at mid-ocean ridges. These mid-ocean ridges are underwater mountain ranges formed by tectonic activity, specifically where tectonic plates are diverging. As the plates pull apart, magma from the mantle rises to fill the gap. As this molten material reaches the ocean water, it cools rapidly, solidifying into new oceanic crust. This process is fundamental to the theory of seafloor spreading, which explains not only the birth of new crust but also the continuous recycling of the Earth's lithosphere. Over time, the accumulation of this new crust continuously reshapes the ocean floor and has a significant impact on geological features and tectonic dynamics. The other choices involve processes that do not directly lead to the creation of new oceanic crust. For example, subduction refers to one tectonic plate being forced under another, which typically occurs at converging plate boundaries, resulting in the destruction, rather than the formation, of crust. The destruction of older oceanic crust is a consequence of subduction rather than a method of creating new crust. Similarly, weathering of surface rocks pertains to surface processes that affect landmasses and has no role in the geological mechanisms