“In fact, it looks as if the Earth is in a state of chemical disequilibrium. Degassing of the core and lower mantle is apparently incomplete, probably implying that the temperature of the deeper parts of the planet has always been moderate – higher temperature and magma pockets being properties only of the outer few hundred kilometres. When extended to the surface, upstanding segments of the C-M boundary tend to correspond to deep oceanic depressions, while ‘topographically’ lower C-M regions accord with the location of the continents and their mantle roots.”