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
The Dog and Its Reflection The Dog and Its Reflection The Dog and its Reflection (or 'Shadow' in several translations) is one of Aesop's Fables and is numbered 133 in the Perry Index. An indication of how old and well-known this story was is given by an allusion to it in the work of the philosopher Democritus from the 5th century BCE. Discussing the foolish desire for more, rather than being content with what one has, he describes it as being 'like the dog in Aesop's fable.' In the story, a dog that is carrying a stolen bone, or piece of meat or cheese, looks