Geology: Principles and methods

Geology: Principles and methods

391 joined forces and maäe the parts flt as well as they have. Ö. ÖZDEMIR and D.J. DUNLOP (Toronto, Canada) Geology: Principles and Methods. J. Derco...

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joined forces and maäe the parts flt as well as they have. Ö. ÖZDEMIR and D.J. DUNLOP (Toronto, Canada) Geology: Principles and Methods. J. Dercourt and J. Paquet Graham and Trotman, London, U.K., 1985, £30.95/$54.00, 230 pp., ISBN 0 86010 485. This book (translated from French) is intended as an introductory text book to the Earth Sciences. It assumes no previous knowledge of the subject but does expect an acquaintance with, or a willingness to learn, basic mathematics, physics and chemistry. Sixteen chapters are divided into four parts, each dealing with a major area of Earth science. Part 1 deals with minerals and rocks. It starts with a treatment of crystallography, atomic structure, and types of bonding, and leads on quickly to the principal groups of rock-forming minerals . From here, the reader is taken rather rapidly through phase equilibria and into the behaviour of magmas and the evolution of basatts, ultrabasic rocks, andesites and granites. A final chapter deals with the solid-state processes responsible for metamorphic rocks. Part 2 concerns the processes operating in the earth's interior and consists of three chapters. The first demonstrates how the structure of the earth can be deduced from seismic and gravity data. Attention is then focussed on the structure of the continents and oceans, and this leads neatly to a discussion of sea-floor spreading and continental drift. This last chapter reviews the observational data in favour of continental drift and ends with plate tectonics and a discussion of the driving forces involved . The third and largest part of the book is entitled, somewhat misleadingly, "Global Dynamics". It is essentially concerned with surface and nearsurface processes. Three chapters on erosion, sedimentation and sedimentary rocks are followed by a discussion of the measurement of geological time, using techniques ranging from radiometric dating to palaeontological and stratigraphic approaches. The arguments developed in these four

chapters are then brought together in two chapters on ancient sedimentary environments and mountain building procxsses. The latter is mostly concerned with the evolution of the French and Italian Alps, but concludes with a brief section on the contrasted development of the Canadian Cordillera. The last part consists of a single but useful chapter,on applied geology. This is concerned with the formation of natural resources and the role of geologists in exploiting and conserving them. The subjects covered in this chapter include geophysical exploration techniques, engineering geology, hydrogeology and oil and mineral deposits. For its size (384 pages) the book covers an astonishing amount of material, a feat achieved by moving at a very rapid pace. The style is concise with short, snappy explanations of what are. frequently difficult concepts. The main strength of the book fies in its demonstration of the important role played by physics and chemistry in an understanding of the earth. It should go a .long way towards dispelling the commonly held belief that geology is largely a qualitative science to which rigorous scientific method cannot easily be applied. This emphasis on the quantitative aspects of the subject is reinforced by the exercises at the end of each chapter. On the negative side, the concise style makes parts of the book difficult to read. This problem is partly overcome by the excellent illustrations and comprehensive index which makes the book very easy to dip into. The rigour of the treatment is variable and presumably reflects the expertise of the authors. Inaccuracies creep in occasionally and range from the trivial (" tholeütic" is not derived from "Thale", p. 41) to the misleading (the treatment of the origin of .basaltic magmas on pp. 56-60, for example) . Such weaknesses are infrequent, however, and do riot seriously undermine the value of the book. Students beginning a course in geology or geophysics, either as a main or a subsidiary subject, will find this book both useful and stimulating: More advanced students and their teachers will benefit from using the book as an introduction to unfamiliar areas. GODFREY FITTON (Edinburgh, U.K. )