IN his recent book on The Geological Aspects of the Origin of Life on Earth, Prof. M. G. Rutten has adopted as his central thesis the postulate that the Earth retained its primaeval reducing atmosphere up to 1,500–2,000 million years ago. This conclusion is based on the premise that the gold–uranium ores of the Witwatersrand (South Africa), Blind River (Canada), and Serra de Jacobina (Brazil) are fossil alluvial deposits, in which the notionally detrital uraninite and pyrite are supposed to have survived weathering because the deposits reputedly accumulated under anoxygenic conditions. Nowhere in his work does Prof. Rutten mention that scores of papers have been written by geologists of international reputation to show that these ore-bodies (‘bankets’) have been formed within the Earth's crust long after the mother-rock sediments were laid down, by the infiltration of hydrothermal metal-bearing solutions. A lengthy review by Prof. J. D. Bernal1 commends this book to Nature's wide circle of readers as “a welcome fresh light on one of the most exciting problems of the day”, the reviewer apparently being unaware that the origin of the Witwatersrand gold deposits has remained one of the most controversial issues of economic geology for more than half a century, and that since the discovery of commercial uranium in these ores the arguments have increased in number, vigour and acerbity. Most geologists will know that both sides of the question are recounted at length in the leading American, French and Russian text-books on uranium geology, as well as in the official publications of the South African, Canadian, and United States Geological Surveys. Other readers, however, should be warned that the validity of Prof. Rutten's conclusions is no greater than that of his fundamental premise, and that this is very debatable indeed.