information:classification, structural:summarization
Tertiary crust

Tertiary crust is more chemically-modified than either primary or secondary. It can form in several ways:

The only known example of tertiary crust is the continental crust of the Earth. It is unknown whether other terrestrial planets can be said to have tertiary crust, though the evidence so far suggests that they do not. This is likely because plate tectonics is needed to create tertiary crust, and Earth is the only planet in the Solar System with plate tectonics.