'In his latest book, Paul Lyle presents a learned, well-designed and readable account of time in a geological context, drawing its title from James Playfairs famous aphorism when reflecting on the enormous length of time revealed by the Siccar Point unconformity. It might perhaps have been subtitled The intelligent persons guide to eternity, as its intended audience is those with a general interest in the natural world, its development and its future.Specifically it is aimed at those making environmental and development policy who should be better informed of the temporal and geological contexts of their decisions. Plentifully illustrated with well-chosen good quality examples, it would also be a valuable source for introductory geology courses and for those working in the peripheral areas of the Earth sciences.Lyle recounts how our thinking about deep time developed historically in the different perspectives of those who have contemplated it, from the ancient and medieval philosophers, through James Hutton and the Scottish Enlightenment, to the famous geologists and theorists of more recent times.He reviews the formative debate about uniformitarianism and catastrophism, introduces the concepts of times arrow and times cycle and presents an elegant and succinct overview of the processes working on and within our planet, as we now understand them.He describes the Earths development since the beginning, using time as a framework to explain the changes wrought on the Earth both by slow earth processes and by isolated events. Finally he examines contemporary phenomena, both natural and anthropogenic, and applies plate tectonic theory to peer further into the future. In the great scheme of things, while some may think of Man as the most significant being on Earth, we are left perhaps to infer that our effect on the planet itself and its ultimate future is likely to be negligible in the very long run.Tangentially, useful and informative accounts are presented of methods of dating, from semi-quantitative approaches of sedimentology and palaeontology, to quantitative radiometric, dendrological and magnetostratigraphic methods.' Geoscientist'For anyone like me who finds the immensity of geological time ('deep time') both fascinating and fundamentally difficult - both emotionally and intellectually - this is a great book. Paul Lyle has written it for environmentalists and policy makers to help them explain their concerns and decisions more clearly in the context of geological time, but these are not the only people who should read it. It covers (among other things) the history of man's efforts to quantify the earth's age (both relatively and absolutely), from the Ancient Greeks and biblical scholars, through the renaissance to nineteenth and twentieth century efforts to reach an absolute figure of about 4.54 billion years. It also covers the grand themes of geology, including the unifying theory of plate tectonics, and shows how an understanding of time is fundamental to geologists. Therefore, anyone with an intellectual interest in geology and why their science is quite different from the others should read the book.As the author explains, fundamental to the concept of geological time are the concepts of the 'Time's Arrow' and 'Time Cycle'. The first refers to non-repeatable aspects of the flow of time (e.g. the extinction of species, and the creation of banded iron and an oxygen rich atmosphere); while the second refers to series of repeated processes (e.g. rock and water cycles, and the cycles of the moon and sun). Both concepts are essential to explain geological processes and both present problems for lay-people to understand.The author clearly hopes that greater understanding of 'deep time' will lead to more awareness of the Earth's vulnerability, as its resources are depleted by consumers and its climates are affected by global warming. We must realise that economic and political decision-making relies on this understanding. For example, the geology involved in creating crude oil (time's cycle) takes so long that, for human beings, once our supplies have gone, they have gone forever (time's arrow).I can recommend this book on a number of levels and thoroughly enjoyed it.' Deposits
