At first glance this book appears to be hard work, with few diagrams and a subject that is not intuitively easy to understand. However the book includes anecdotes and strange facts which enliven the prose, and it covers a much wider range of topics than you might think from the title. These include what magnetism is, the shape of the Earth's magnetic field (not the simple 'field-around-a-bar-magnet' shape you often see illustrated), what happens when the magnetic field reverses, how the field is formed. It looks at how the Earth's field interacts with the Sun, including geomagnetic storms, and takes a look at how geomagnetism helped to unravel plate tectonics. There are also chapters on animals using magnetism for navigation.

There is a short appendix in the back which includes some of the more technical details, and a comprehensive set of notes that expand on some points in the main text. There is no bibliography, but some other relevant books are mentioned in the notes.

Well worth reading if you are interested in magnetism or Earth sciences.