Principles of applied geophysics

77 general history of geomorphology during the "Davis Era" and a final volume on geomorphology post World War I1. The authors have produced the first fulllength biography of William Morris Davis. It represents, they tell us, ten years of effort. One can believe them. In addition to the voluminous published writings of Davis they have sought out and recorded vast quantities of letters to and f r o m Davis as well as other documents relating directly to his w o r k and life. In addition they have interviewed or corresponded w i t h some 250 individuals who had known Davis or who had access to specific information. The volume that emerges is long and is replete w i t h the useful paraphenalia of a such a venture. In general the authors elect to let Davis speak to us through the written record. They rely not only on his published w o r k , but even more heavily on the extensive unpublished documents, largely letters. They adopt the technique of supplying their own words as connective tissue to weave together the words of Davis and his contemporaries. A reasonable estimate is that over half of the book is quotation. Because each quote is set in smaller face than that of the authors' narrative the reader gets a full measure of words per page. Illustrations include a number of photographs of Davis en famille or on field excursions and a large number of his own drawings, most being reproduced f r o m the original articles. In sum, it is a long volume and demands close reading. This reader has profited and let me more specific. Aside f r o m the authors' I doubt if there are many w h o have read Davis's w o r k completely through, or have read even the more important ones which began in 1889. A great deal of Davis is slow going at best. The authors have done us a service by extracting the most salient portions of the master's papers and giving the corpus of Davis's w o r k a coherence that w o u l d be most d i f f i c u l t if not impossible for lesser mortals to achieve. Davis was a giant. He was possessed of great energy, a keen mind, a productive and persuasive pen. He was a one-man crusade whose ideas dominated the study of tandforms for half a century. But what else? The letters, interviews, and activities of Davis give the reader a more intimate view o f the

man. The impressions are contradictory, because the man was contradictory. To this reader he often comes through as a cold, somewhat aloof, demanding, self-centered and stubborn person. Then one finds him to be, or at least wanting to be, an affectionate parent, a loving husband, an approving mentor, and one w h o was often lonely but seldom loved. I found myself reading the book against the background and events of the 84 years of Davis's life. One gets some idea how he effected others and they him. For instance the relations w i t h the Pencks, older and younger are fascinating as are those with their German contemporaries. The problem of promotion to tenure that Davis faced early in his career is intriguing and has many modern counterparts. I expect we will see in the third volume a more direct concern w i t h the play of ideas and personalities that mark the Davisian era. In the meantime, and thereafter, this volume will stand as an impressive source book for those interested in Davis, his life, and his work. S. Judson, Princeton, N.J.

APPLIED GEOPHYSICS D.S. Parasnis, 1972. Principles of Applied Geophysics. Chapman and Hall, London, 2nd ed., 214 pp., 66 fig., 11 tables, £ 2.00. This is the second edition of the introductory t e x t on applied geophysics which was originally published as a monograph in 1962. In this edition the author has made use of the o p p o r t u n i t y to revise some parts and to add a number of topics of practical importance in geophysical prospecting. An outstanding feature of the new edition is the adoption of the "Syst~me Internationale" (Sl) that has been used for nearly all units. Structurally, the book has retained the original f r a m e w o r k and contents of the first edition, w i t h relative emphasis on electrical and electromagnetic methods which occupy almost one-third of the space. The chapters covering these methods are quite thorough and contain topics of relatively recent origin, including the Kernel function of resistivity,

?8 induced polarization, and transient and V.L.F. techniques. The discussion of these methods is probably the best that can be found in introductory books of similar scope. The chapters on gravitational, magnetic and seismic methods are somewhat short in summarizing the important aspects and practical applications. Significant omissions that can be pointed out are: The problem of regional-residual separation in gravity, the use of palaeomagnetism as a structural and correlation tool, the use of magnetics in oil exploration, the refraction mapping of faults and salt domes, and seismic investigations of deep sedimentary basins. In seismics, the reflection method has been treated sufficiently well, covering most of the modern aspects. I n magnetics, one novel feature is the treatment of magnetic anomalies of thick sheets. The three final chapters give compact accounts of radioactive methods, airborne surveying and miscellaneous methods. These are reasonably up-to-date in so far as the recent developments are concerned. A regrettable exception is the treatment of geothermal methods, which is very brief and inadequate. To condense the principles and practices of all the geophysical methods in some 200 pages in a pocket-size book is a difficult task. Seeing the limitations of space, the author has accomplished a remarkable feat of putting together a number of important "facts, valuable experiences and an overall view of the ~vide subject. This reviewer felt that some space could have been saved by eliminating descriptions of certain outdated instruments (such as the Ehtvhs torsion balance, T h a l e n Tiberg magnetometer), and used to better advantage by including some of the important aspects mentioned above. However, these are minor reservations and, on the whole, Parasnis' book is a very timely and valuable contribution to the literature in geophysical exploration. The book should be read and reread by students and explorationists to digest the great deal of information it contains. P.V. Sharma, Copenhagen

EARTHQUAKES IN THE FAR EAST V.N. Aver'yanova, 1973. Seismic Foci in the Far East. (Translated from Russian.) Wiley, Chichester, 207 pp., £ 8.45. The author presents 530 fault plane solutions obtained for earthquakes in the Kamchatka--Kurile--Hokkaido region. Most of the earthquakes occurred during the period 1952 to 1964. The data, the method of analysis and the earthquake source model on which the method is based are clearly and thoroughly presented. The resultant fault plane solutions are subjected to statistical analysis, classified into distinct groups, and discussed in the context of general seismicity and crustal structure of the region. The book was published in Russian in 1968, and most of the works were done before the era of plate tectonics. Naturally, I was most interested in the conclusion of this book in relation to the prediction of plate tectonic theory. One of the major conclusions is in harmony with the plate theory. The normal fault with the tension axis more horizontal than the compression prevails in the belt of the deep-sea trench. This result is consistent with the tension due to bending of the plate under the'trench. Stauder discovered a similar result for the Aleutian earthquakes in support of the plate theory. Reverse faults were found prevailing in the main seismic zone north--west of the trench, in harmony with down-thrust of the plate. An idealized earthquake expected from the plate theory for this region is a pure dip-slip thrust fault on a low-angle fault plane with dip angle about 20 ° . According to Kanamori's analysis of long-period body and surface waves, the Kuril earthquake (M = 8~4) of Oct. 13, 1963 was such an idealized earthquake. The fault plane solution given in the book for the same earthquake is also a thrust fault, but with a considerablestrike-slip component on a much steeper fault plane. The steep fault plane (dip angle around 60 ° ) and large strike-slip component are common for most earthquakes studied in the book. The author's data are primarily from station bulletins. Therefore, more inconsistencies are expected than the method based on the reading of long-period P waves