The authors' intention in this book is to provide a treatment of the physical processes that are responsible for plate tectonics and other geological phenomena in a manner that is accessible to senior undergraduate and graduate students of diverse backgrounds in the physical and earth sciences. To this end, they have divided the subject into eight sections, preceded by a brief introduction to plate tectonics. This is perhaps the least felicitous chapter of the book: Summarizing plate tectonics, its driving mechanism and our knowledge of the inner planets, their satellites, and the Galilean satellites in about 30 pages of text is not a trivial undertaking, and while I have read several far worse attempts, I doubt that this chapter will give a clear idea of geodynamics to, say, the average engineering student. Part of the problem lies in the breathless rush through an immense amount of material, some of which is still in a state of flux, and part lies in the curious organization of the material. It seems strange, for example, to put a section on the structure of the continents after sections on accreting plate margins, subduction, and transform faults and before a discussion of paleomagnetism, plate motion, and triple junctions, and stranger still to make this section principally an introduction to geochronology.