Crust (geology) depth, reaching values typically in the range from about to at the boundary with the underlying mantle. The temperature increases by as much as for every kilometer locally in the upper part of the crust, but the geothermal gradient is smaller in deeper crust. The continental crust has an average composition similar to that of andesite. The most abundant minerals in Earth's continental crust are feldspars, which make up about 41% of the crust by weight, followed by quartz at 12%, and pyroxenes at 11%. Continental crust is enriched in incompatible elements compared to the basaltic ocean crust and much
Crust (geology) Mars comprise secondary crust, as do the lunar maria. On Earth, we see secondary crust forming primarily at mid-ocean spreading centers, where the adiabatic rise of mantle causes partial melting. 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