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Itydrothermal Uranium Deposits is virtually identmal to, but much more easily used than, a 383-page open-file report (GJO-1640) prepared by the authors for the U.S. Energy Research and Development Administration in October 1975. I recommend this book for all teachers, explorationists, stu- dents, or researchers studying uranium deposits.

J.T. NASH Denver, Colo.

G~ologie de l'Afrique. Le Craton Ouest Africain. Bernard Bessoles. B.R.G.M., Paris, 1977, 403 pp., F.F. 190.00, $ 38.00.

For ty years ago, large areas of the African continent were still geologically unexplored and our total knowledge of the geology of Africa was contained in the four volumes of Krenkel's treatise. Since then, considerable progress has been made, blanks have disappeared on the geological maps and some districts are now studied in considerable detail. However, the results of these works, particularly in the case of the Precambrian, are scattered in innumerable papers and unpublished reports many of which are difficult for researchers to obtain. We must congratulate Bernard Bessoles on his enterprise in gathering the main data in a series of books, each of which focuses on a large geological unit, such as cratons and mobile belts for basement rocks.

The first volume, which has just been published, is devoted to the West African craton, defined as that area consti tuted by Precambrian terranes the radiometric ages of which appear to be earlier than 1400 Ma. After a general presentation of the craton, the book is divided into four parts: the "dorsale reguibat" in the North West; the "fen~tres de Kayes et Kenieba" in the West; the "dorsale de Man" in the South; and the intrusive basic rocks. In each section the main regional units are analysed in detail. The author then attempts to elucidate possible correlations and geological evolution. Substantial abstracts with English translations guide the reader through the multiplicity of local series names. In a general conclusion some comparisons are outlined with other cratons recognized in Africa, South America and Australia.

Obviously, geochronology is the main thread running through this at tempt to establish general chronology and correlations; but the meaning of data are often questionable. Unfortunately, accurate structural data are restricted to a few district areas and petrological considerations are too often insignificant making it difficult to form a suitable opinion on many structural units. Of course we must not forget ~he great complexity of Precambrian geology and the difficult conditions under which most of the results were obtained in a short space of time.

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We must appreciate the great objectivity of the author in the presentation of conflicting observations and interpretations due to numerous investigators but also the clear and moderate expression of his own opinions. However it is unfor tunate that no general map gathers together the main geological data at present accepted on the West African craton. The omission of any reference to mineralization is surprising.

This book constitutes an indispensable working tool to all those interested in African geology. Presenting our up-to-date knowledge in considerable detail, with an extensive bibliography, it not only incites reflection on many controversial topics bu t also indicates the direction necessary if future progress is to achieve a fuller understanding of the African Precambrian.

MAURICE LELUBRE Universitd Paul Sabatmr, Toulouse

Patterns o f Evolution as Illustrated by the Fossil Record. A. Hallam (Editor). Elsevier, Amsterdam, 1977, xiii + 591 pp., Dfl. 170.00.

The past 15 years has witnessed a renaissance in paleontology, a revitalization which has largely redirected the course of the science toward its definitive aims - the study of ancient life. This "purification of effor t" , however, has not produced a consensus solution to several fundamental evolutionary issues (Gould's "external metaphors") which provide the focal point for Hallam's book: (1) Is the evolutionary cause produced by external environmental forces acting on a plastic genotype; or do " independent" internal genetic changes yield adaptive solutions to the environment?; (2) Is the evolutionary effect on taxonomic diversity and morphology directional, or steady state?; and (3) Is the character of the evolutionary dynamic gradualistic within and among taxa, or episodic, thereby interrupting nominally static genotypes? Patterns (and by implication, paleobiologists in general) has been severely criticized for failing to achieve compelling solutions to the above issues. Never- theless, Patterns succeeds admirably: it provides an excellent series of concise paleobiological statements on the fossil record of major taxa, formulated within an evolutionary context. Most major groups of fossil metazoans are treated, but conspicuously lacking are such intriguing groups as the Archaeocyatha, Stromatoporoidea, Porifera, and Coelenterata, all of which have undergone exciting paleobiological reappraisals in recent years. Also conspmuously absent is any specific t reatment of Precambrian evolution.

A major strength of Hallam's book lies in its organizational structure. The first three chapters establish a conceptual and interpretational framework: (1) the metaphoric issues that constitute the conceptual nature of the evolutionary phenomenon [Gould] ; (2) the broad concept of the adaptive