Geodesy is devoted to the determination of the shape, size, and gravity field of the Earth. Its methods include triangulation, leveling, gravity surveys, and tracking by artificial satellites. The results of its observations typically hold for time periods varying from a few hours to decades. In contrast, in geophysics (seismology in particular) one deals with very short periods of an hour or less, while in geological processes, one frequently considers periods of a million years or more. In Lambeck's book, the author treats the middle ground between these two geophysical extremes, which is concerned with the slow deformation of the Earth. He quite appropriately calls this geophysical geodesy, and its topics include crustal motion, spatial and temporal variation of the gravity field, rotation, and tidal deformations of the Earth. Hence geophysical geodesy aims to bridge a traditional gap between geodesy and geophysics.