Melting the Earth: The History of Ideas on Volcanic Eruptions

The last words in the subtitle of this excellent book are somewhat misleading, as this is a history of concepts of magma generation rather than eruption. Haraldur Sigurdsson traces the evolution of ideas on the generation of heat within the Earth, from the ancient view that air in subterranean voids was compressed by ocean waves and tides, through combustion of fossil fuels, remnant heat from a primeval hot Earth, and exothermic reactions, to radioactive decay. In addition to sources of heat, its mechanism of transfer, the process of melting, the identity of the material being melted, and the depths at which magmas were generated were subjects of early inquiry by D'Arezzo, Michell, and Spallanzani, among others. Most 19th century geologists, however, followed Charles Lyell in his reluctance to speculate on causes. This left the field to William Hopkins, Gustav Bischof,and others whose names are not well known to 21st century penologists. The large cast of players in this book also includes the ever‐popular Desmarest, Hamilton, Holmes, Hutton, and Scrope, and an occasional scoundrel. The last chapter, on the source of magmas, makes no mention of contributions from trace element and isotope geochemistry and none concerning high‐pressure minerals that indicate localized deep burial of continental crust and ascent of material from the lower mantle.