Menard's subject is oceanic (volcanic) islands — including coral atolls, banks, and guyots (submarine mountains) — rather than "continental" islands such as New Zealand or the Seychelles. He begins with an account of the successive discoveries of the world's islands (by plants, by animals, by the Polynesians and other island peoples, and finally by Europeans). He then explains the basics of plate tectonics, which is the key to understanding the creation, distribution, and history of islands. Other factors which play a major role in their history are changes in sea level and the presence or absence of coral: the full story is complex but satisfying well understood. Menard goes on to look at interactions between islands, with the load from some flexing plates and causing others to rise or sink, and the fates of islands as they are subducted into trenches or obducted onto continents. He concludes with a brief look at island life from a geological viewpoint.
Islands is not at all technical (like Scientific American itself, it assumes only a general scientific background), but it provides detail wherever it helps to explain the broader picture. Whether it is the link between cold, fertile, upwelling waters, large concentrations of sea birds, and phosphate deposits derived from guano, the balance between thermal subsidence and isostatic uplift following erosion, or the complex history of the Hawaiian island chain, Menard explains the essential intricacies involved adroitly. Having read accounts of the Polynesian colonisation of the Pacific, histories of European exploration, ethnographic studies of island peoples, and studies of island biogeography, it was a lot of fun to see the same places from the multi-million-year perspective of the geologist.