322 BOOK REVIEWS

(composite basement) that detach within the thermally softened ductile-brittle transition zone, and Type F--fold-related lobe shaped thrust sheets that form below or within the brittle/ductile transition zone by attenuation of the common limb between antiforms and synforms. Examples are drawn from several mountain belts in this largely field based pre- sentation. Ramsay presents an important word of caution by using field examples to suggest that there has been a tendency to overplay the geometry of classic fold and thrust models and to force too readily the geometry of naturally developed thrust systems into these models.

The final sections, forming about half the volume, contain sixteen papers that discuss thrust and fold geometries and crustal struc- ture from parts of or entire orogenic belts. Ex- amples are presented from the Pyrenees, Alps, Himalaya and the northwest American Cordil- lera. Through combining surface geology and deep seismic profiles the crustal structure of certain orogens is becoming much better known. This is particularly true for the Pyre- nees (the subject of several papers) where a rather comprehensive evolution can be con- structed. Shortening by northward subduction of a thinned Spanish lithosphere, inversion of extensional basins, backthrusting in the North Pyrenees and the allochthonous nature of the North Pyrenean fault play significant rolls. Even in the long studied Western Alps major new interpretations continued to be made. Laubscher suggests that several diverse fea- tures in the Alps be explained by a diffuse zone of right-slip passing from the Insubric line through the Lepontine region and into the marginal structures along the southwestern part of the mountain belt. Unroofing of the high- grade Lepontine core may have been partly the result of extension in a decoupled upper crust along this diffuse shear zone.

The full diversity of this volume can not be presented in such a short review. Overall the volume is useful by presenting advances and recent thinking on fold thrust belts and oro-

genic processes in general. It is by no means complete, but goes a long way to show how in- terdisciplinary and multifaceted research in thrust tectonics has become. It is a very useful volume for both researchers and students.

B.C. BURCHFIEL Cambridge. MA. USA

Applied Geophysics. W.M. Telford, L.P. Gel- dart and R.E. Sherrif. Cambridge Univer- sity Press, Cambridge, 1991. xx+770 pp. Hardcover. Price £65.00. ISBN 0-521- 32693-I. Paperback. Price £25.00. ISBN 0- 521-33938-3.

This is the second edition of the well known book Applied Geophysics. The highly regarded first edition was issued in 1974. I was imme- diately impressed with the quality and scope of the new completely revised edition of the book now expanded to 770 pages. The SI units have been adopted but they are supplemented with the older historical units where the older units are still current. The subject matter is divided into 12 chapters together with 2 appendices and an extensive index. The book is full of dia- grams, charts and examples which enhance the text and at the end of each chapter there is a fine set of problems set as exercises. The book assumes that the reader has a background in physics and mathematics, and familiarity with the terminology of geology. Following a short introduction on the development and applica- tion of applied geophysical methods, there are chapters encompassing: gravity (56 pages); magnetics (pages 74); seismic (147 pages); electrical properties of rocks and minerals ( 10 pages); natural electrical sources (50 pages); electromagnetic ( 179 pages); resistivity (56 pages); induced polarisation (33 pages); ra- dioactivity (34 pages); well logging ( 55 pages); integration of geophysical methods (27 pages).

In each chapter the general approach is to describe the geologic circumstances under which the method can be used to advantage to locate deposits of commercial significance, fol- lowed by a straightforward but thorough treat-

BOOK REVIEWS 323

ment of the basic theory of the method. Next discussed is the equipment to be used followed by the techniques of data acquisition. Finally the methods of data processing and interpre- tation with the objective of finding and deter- mining the extent of mineral or hydrocarbon deposits are examined. The rapid develop- ment of solid state digital equipment, and its ready interfacing to computers for data pro- cessing has made an up-to-date book impera- tive. Improved instrumentation with its con- sequential increased data gathering ability, combined with the processing power of mod- em computers has opened up new methods of interpreting the data. It is particularly satisfy- ing to find these important changes reflected in the presentation of the material in the new edition of the book. Specifically, in the sec- tions dealing with the processing of data, the solution of inverse problems subject to a few reasonable geologic constraints, has assumed increased importance.

The second edition is now in a two-column format for text with many of the diagrams oc- cupying page width format for impact and clarity. Every chapter has a well-selected group of references that provides to graduate stu- dents and professional geophysicists, a ready access to specific specialised material avail- able from other sources. Particularly for un- dergraduate students, each chapter has a set of instructive problems taken from the real world.

It is an excellent book. It has been produced as a suitable textbook for a serious undergrad- uate course in geophysics for geophysicists, en- gineers and geologists. It provides a most com- prehensive and thorough treatment of the subject matter in all the fields of geophysical prospecting. The professional geophysicist and other practicing earth scientists will find the book readable, concise, and most useful as a reference work. At the recommended retail price, the book is excellent value for money.

RONALD GREEN Arrnidale, NSW, Australia

Discontinuity Analysis for Rock Engineering. Stephen D. Priest. Chapman and Hall, Lon- don, 1992. Hardcover. Price £35.00. ISBN 0-412-46700-2.

A particular feature of the development of discontinuity analysis for the design of under- ground structures in massive rocks over the past 20 years has been the way in which the practical engineering approach to an essen- tially complex engineering problem has been reduced to simplistic levels by the widespread adoption of empirical classification systems and simple analogs. The justification for this type of approach is the essential simplicity of design, excavation and support of most sur- face and underground structures when com- pared with the complexity of most rock mass discontinuity systems. A secondary reason is the lack of satisfactory constitutive models of discontinuous rock mass deformation and fail- ure. This is the background to Priest's book, and to his stated intention "to apply the math- ematical methods of probability theory, statis- tics, vector analysis and mechanics to a topic that has previously been handled in a largely qualitative way".

The problem in rock mass modeling, whether of deformation or flow, is to determine the vol- ume, pattern and interconnectivity of discon- tinuities. This is a complex function of discon- tinuity orientation, density and size modified by spatial distribution, the intrinsic rock strength and deformability, and the imposed or natural stress regime, and it determines both the permeability, stability, and compressibil- ity of a rock mass. It requires a numerical ap- proach, but it also requires a methodology ac- ceptable to geologists and engineers for collecting, processing and describing individ- ual discontinuities and discontinuity sets and systems.

The approach of the book (outlined at the end of chapter 2) is to identify the main pa- rameters (defined here as strength, number and orientation of discontinuity sets, set fre-