The Inaccessible Earth: An integrated view to its structure and composition

This is the second edition of a unique treatment of the origin, structure and internal composition of the Earth, and synthesizes the geological, chemical and physical knowledge bearing on the Earth's inaccessible interior. It is an integrated and readable account suitable for undergraduate students and teachers of the Earth Sciences. Why do we think that the centre of the earth is a nickel-iron alloy; or that the crust evolves by processes at spreading ridges, subduction zones and where plumes rise near the surface, or that the Earth's magnetic field is generated by convection in the molten outer core? The evidence comes from many disciplines but the contributions of geophysics and geochemistry are particularly important. The text traces how the Earth's layered structure is revealed by seismic data and examines the variation of density with depth by combining knowledge of the Earth's mass and moment of inertia, deduced astronomically. Density is the prime constraint on chemical composition which is deduced also by reference to new theories of stellar evolution and planetary accretion, combined with evidence from the solar system and meteorites. The second half of the text goes on to describe the probable composition and physical state of the present day core, mantle and crust. In the second edition, more emphasis is placed on dynamical processes at all depths in the Earth. These are a consequence of various forms of convection powered by heat released by radioactive decay and the cooling of the Earth. Effects such as mantle convection and the geomagnetic dynamo are reexamined in the light of our improved understanding, and geological evidence is used to construct a model for the evolutionary history of the Earth's continental crust.