For a student of geology, this is an excellent book, but for the average reader it is entirely too technical and detailed. Even as a chemical engineer who frequently reads scientific journals, this reader found the book to be a struggle. Still, it provides superb insight into the real world of scientific discovery, showing how personal interactions, circumstance, and serendipity play critical roles. It was well worth reading in its entirety. The author has obviously gone to great lengths to produce a thorough account of how reversals in the earth's magnetic field, dated by radioactive decay, came to be understood and used to prove seafloor spreading and continental drift.