Earth’s mantle is the thick layer of silicate rock between Earth’s crust and its molten core, making up about 84% of our planet’s volume. The mantle is predominantly solid but, on geologic time scales, it behaves as a viscous fluid—as difficult to stir and mix as a pot of caramel.
Click here for original story, New model shows Earth’s deep mantle was drier from the start
Source: Phys.org