Riddles in Stone covers a variety of fascinating controversies and startling differences of opinion that accompanied the evolution of the study of Earth Sciences in southern Africa. Over the centuries, debates have raged amongst geologists, and between geologists and biologists, physicists and theologians, on controversies such as the age of the Earth and its lifespan; Continental Drift; the origin of ore deposits of gold, diamonds, copper and platinum; and Schwarz’s well-meaning but forgotten Kalahari Scheme.

Although scrupulously rooted in scientific literature, this  book main tain s an accessible and entertaining tone and shows how con sensus amongst a majority may be proof of nothing. Geologists, challenged to interpret events that took place billions of years ago, have drawn up theories and hypotheses which may appear either absurdly dated or, from other perspectives, as cutting edge. The introduction of fresh ideas (as in the Plate Tectonic model) or new techniques (as in the dating of rocks using radioactive decay) can realign the thrust of science, leading to the aban donin g of traditional ideas and the embracing of new ones.

Hugh Eales is Professor Emeritus of Geology at Rhodes Univers ity, South Africa.