What characteristic distinguishes oceanic crust from continental crust?

The characteristic that distinguishes oceanic crust from continental crust is its thickness. Oceanic crust is generally thinner than continental crust, typically averaging about 5 to 10 kilometers in thickness, whereas continental crust averages about 30 to 50 kilometers. The difference in thickness is a key factor in their structural formation and composition.

Continental crust is composed mainly of lighter, granitic rocks which contribute to its greater thickness and buoyancy. In contrast, oceanic crust is primarily made up of denser basaltic rocks, which are not only thinner but also denser than the materials comprising continental crust. This fundamental difference in thickness helps explain various geological features and processes related to tectonic activity, such as the formation of ocean basins and mountain ranges.

As for the other options, while oceanic crust has a higher density and often greater iron content compared to continental crust, it is the significant difference in thickness that primarily differentiates the two.