The highest proportion of volcanoes, earthquakes and geysers occurs around the rim of the Pacific Ocean, aptly called the circle of fire. The book accounts for this fact and also explains a good deal of basic geology in describing the way in which each of these violent activities proceeds. The most comparably thorough accounts are in two different books, Buehr's Volcano! and Roberts' Our Quaking Earth. Here Heintze has succeeded in combining excellent sections on volcanoes and earthquakes, the common focus being the great circle of fire. The bibliography is rather slight in both quantity and quality; otherwise it is thorough and altogether useful.