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Rock dynamics and geophysical exploration
94
while the preface claims that the emphasis in the b o o k is on " e x p l o r a t i o n geology", I can find little overt dedication to this in the text. A serious deficiency is the general lack o f chemistry of reactions of formation of minerals and of alteration processes; the amount of data now available is enormous, and it should be collated and made available to students in a book of this type. Comments on literary idiosyncrasies are generally indefensible, but since I have rigorously denied generations o f students the use o f the adjectives "intrusive" and "volcanic" in the pseudo-noun form of "'intrusives" and "volcanics", I am somewhat dismayed to find the book liberally sprinkled w i t h them. These negative comments should not detract f r o m the achievement of Professor Park and the late Professor MacDiamird in originally writing this volume and Professor Park's diligence in revising it. It remains virtually the only t e x t b o o k on economic geology as it is understood by most North American geologists, and, given the virtual explosion of geological w o r k relevant to the field, it is probably not now possible to adequately encompass the field in a single t e x t except in an introductory manner. In the sense that careful field observations are fundamental to good geology, the detailed descriptions of the field relations of the ore deposits described are indispensable. The deposits chosen for description are, for the most part, good type-examples, and there are representatives from all continents. The book is well illustrated with clear diagrams, and the reference lists give a broad and upto-date coverage of the subject matter. G.J.S. Govett, Fredericton, N.B.
ROCK DYNAMICS L.N. Persen, 1975. Rock Dynamics and Geophysical Exploration. Elsevier, Amsterdam, 276 pp,, U.S. $ 32.50. This book is an a t t e m p t by the author to present a theoretical basis for the study of stress waves in rocks and to show how this theory can be used to predict experimental results which occur when explosives are
detonated in rocks. The actual subject matter covered is much more restricted than is implied by the title. The first seven chapters develop the basic theoretical concepts. Fairly sophisticated mathematical ability is required to f o l l o w these theoretical developments, Chapter 1 develops in twelve pages the basic equations for the state of stress and strain, the equations of m o t i o n and the phenomenological relations between stress and deformation for both an elastic and a Kelvin medium. The final results are summarized for rectangular, cylindrical and spherical coordinates. Chapters 2, 3 and 4 consider in order plane, spherical and cylindrical stress waves in an elastic medium. Laplace transform techniques are used to solve specific boundary value problems such as the application of step function pressure pulses and rectangular pressure pulses to surfaces o f solids of different symmetrical shapes. Chapter 5 considers the application of sinusoidal pressure pulses applied to surfaces of an elastic medium for plane, cylindrical and spherical symmetry. Chapter 6 deals with plane waves in a Kelvin medium. Most of the elastic problems considered in the earlier chapters a?e solved for the viscoelastic medium and the basic differences in the results noted. Similarly Chapter 7 solves the same elastic problems having spherical symmetry for the case of a Kelvin medium. The concept of a signal propagation velocity is developed in this chapter. In these theoretical developments all differential equations are reduced to dimensionless quantities before solutions are obtained. This technique makes for some simplification in the mathematics but results in more difficulties in the comparison of theory to experimental results. Chapters 8 through 11 discuss in detail the interpretation of experimental data from short cylindrical charges in drill holes which are assumed to approximate spherical charges in spherical cavities. Two quantities are measured, strain and acceleration. However, no information is given about the characteristics of the gages or the recording equipment. The experimental results from a number o f standard linear array experiments are analyzed for the propagation laws as straight lines on log--log coordinates. ]-he
95
results f r o m these analyses are used to show that the theory for a square pressure pulse applied to a spherical cavity in a Kelvin medium can be used to predict the observed physical phenomenon, Chapter 12 considers the interpretation of strain and acceleration data f r o m surface explosions. Again standard linear array experiments are used to obtain the basic data. Propagation laws are developed to show that the results agree with the basic theory for stress propagation in a Kelvin medium. The last t w o chapters consider some practical problems, such as safe distances from surface explosions and collapse of tunnels f r o m incidentical shock waves. This book should serve as an advanced engineering reference for dynamic rock mechanics engineers interested in considering rock as a Kelvin medium. Both the theory and the method of data interpretation for strain and acceleration obtained from standard linear array experiments are given in detail. However, the book does not consider other methods of data analyses or compare the results with these other methods. A major defect of the book is the lack of sufficient references to other sources of information on the subject of dynamic rock mechanics. As the subject matter covered is very limited in scope the book will serve more as an engineering reference rather than a t e x t b o o k for a graduate course in dynamic rock mechanics. W.l. Duvall, Lakewood, Colo.
LOESS LITHOLOGY I.J. Smalley (Editor), 1976. Loess Lithology and Genesis. Dowden, Hutchinson and Ross, Stroudsburg, 429 pp., U.S. $ 35.55. The philosophy behind the "Bench mark Papers in Geology" of collection, sifting and rediffusion of specialist scientific literature must be commended. The volume under review undoubtedly presents a well ordered collection of papers but in the end leaves one with a sense of disappointment, not with the inclusions, rather the omissions. The papers themselves are generally of a high standard and provide a useful chrono-
logical sequence which deals with many aspects of the problem of Loess f o r m a t i o n . However, as the expert editor states in his introduction "one could propose to divide the views on Loess into 'pedological' and 'geological' . . . the respective views are (of) the USSR and the United States". The introduction very properly exhorts workers in this field to reconcile the views of the theorists; it is therefore regrettable that the o p p o r t u n i t y to attain this objective presented by this compilation was not taken and pursued with greater vigor. For, as the editor acknowledges in his preface, the Russian literature is underrepresented in this volume. The papers which have been presented represent to a large extent the Western viewpoint and the editor brings the variety of opinions and aspects of this viewpoint clearly to the reader's attention, although he is reticent in passing his own opinion when he is comparing authors' opinions. The papers deal principally with the origin of the majority of the major Loess deposits found in the world with the notable exception of the Chinese and Russian deposits which receive minimal attention. Genesis, however, embraces not only origin but also subsequent secondary soil-forming processes including the f o r m a t i o n of secondary minerals and diagenic processes. It is conceivable that the inclusion of papers on physico-chemical aspects would t h r o w light on the problem of reconciling the t w o main theories of Loess formation. Although it has been indicated that the book lacks balance, nwvertheless the papers chosen present a broad view of those deposits which are the principal topic of discussion. They guide the reader in an able manner, through the history of opinion f r o m 1834 to 1973 with an emphasis on w o r k carried out since 1950. The subject index is full and comprehensive as is the authors' citation index. The mode of presentation, with the editor's specific comments preceding a distinctive set of papers ensures logical grouping and the book is well produced with a clear and fully documented list of contents. The figures are well and clearly presented and have been chosen carefully to complement the edited text. A minor blemish is in the
while the preface claims that the emphasis in the b o o k is on " e x p l o r a t i o n geology", I can find little overt dedication to this in the text. A serious deficiency is the general lack o f chemistry of reactions of formation of minerals and of alteration processes; the amount of data now available is enormous, and it should be collated and made available to students in a book of this type. Comments on literary idiosyncrasies are generally indefensible, but since I have rigorously denied generations o f students the use o f the adjectives "intrusive" and "volcanic" in the pseudo-noun form of "'intrusives" and "volcanics", I am somewhat dismayed to find the book liberally sprinkled w i t h them. These negative comments should not detract f r o m the achievement of Professor Park and the late Professor MacDiamird in originally writing this volume and Professor Park's diligence in revising it. It remains virtually the only t e x t b o o k on economic geology as it is understood by most North American geologists, and, given the virtual explosion of geological w o r k relevant to the field, it is probably not now possible to adequately encompass the field in a single t e x t except in an introductory manner. In the sense that careful field observations are fundamental to good geology, the detailed descriptions of the field relations of the ore deposits described are indispensable. The deposits chosen for description are, for the most part, good type-examples, and there are representatives from all continents. The book is well illustrated with clear diagrams, and the reference lists give a broad and upto-date coverage of the subject matter. G.J.S. Govett, Fredericton, N.B.
ROCK DYNAMICS L.N. Persen, 1975. Rock Dynamics and Geophysical Exploration. Elsevier, Amsterdam, 276 pp,, U.S. $ 32.50. This book is an a t t e m p t by the author to present a theoretical basis for the study of stress waves in rocks and to show how this theory can be used to predict experimental results which occur when explosives are
detonated in rocks. The actual subject matter covered is much more restricted than is implied by the title. The first seven chapters develop the basic theoretical concepts. Fairly sophisticated mathematical ability is required to f o l l o w these theoretical developments, Chapter 1 develops in twelve pages the basic equations for the state of stress and strain, the equations of m o t i o n and the phenomenological relations between stress and deformation for both an elastic and a Kelvin medium. The final results are summarized for rectangular, cylindrical and spherical coordinates. Chapters 2, 3 and 4 consider in order plane, spherical and cylindrical stress waves in an elastic medium. Laplace transform techniques are used to solve specific boundary value problems such as the application of step function pressure pulses and rectangular pressure pulses to surfaces o f solids of different symmetrical shapes. Chapter 5 considers the application of sinusoidal pressure pulses applied to surfaces of an elastic medium for plane, cylindrical and spherical symmetry. Chapter 6 deals with plane waves in a Kelvin medium. Most of the elastic problems considered in the earlier chapters a?e solved for the viscoelastic medium and the basic differences in the results noted. Similarly Chapter 7 solves the same elastic problems having spherical symmetry for the case of a Kelvin medium. The concept of a signal propagation velocity is developed in this chapter. In these theoretical developments all differential equations are reduced to dimensionless quantities before solutions are obtained. This technique makes for some simplification in the mathematics but results in more difficulties in the comparison of theory to experimental results. Chapters 8 through 11 discuss in detail the interpretation of experimental data from short cylindrical charges in drill holes which are assumed to approximate spherical charges in spherical cavities. Two quantities are measured, strain and acceleration. However, no information is given about the characteristics of the gages or the recording equipment. The experimental results from a number o f standard linear array experiments are analyzed for the propagation laws as straight lines on log--log coordinates. ]-he
95
results f r o m these analyses are used to show that the theory for a square pressure pulse applied to a spherical cavity in a Kelvin medium can be used to predict the observed physical phenomenon, Chapter 12 considers the interpretation of strain and acceleration data f r o m surface explosions. Again standard linear array experiments are used to obtain the basic data. Propagation laws are developed to show that the results agree with the basic theory for stress propagation in a Kelvin medium. The last t w o chapters consider some practical problems, such as safe distances from surface explosions and collapse of tunnels f r o m incidentical shock waves. This book should serve as an advanced engineering reference for dynamic rock mechanics engineers interested in considering rock as a Kelvin medium. Both the theory and the method of data interpretation for strain and acceleration obtained from standard linear array experiments are given in detail. However, the book does not consider other methods of data analyses or compare the results with these other methods. A major defect of the book is the lack of sufficient references to other sources of information on the subject of dynamic rock mechanics. As the subject matter covered is very limited in scope the book will serve more as an engineering reference rather than a t e x t b o o k for a graduate course in dynamic rock mechanics. W.l. Duvall, Lakewood, Colo.
LOESS LITHOLOGY I.J. Smalley (Editor), 1976. Loess Lithology and Genesis. Dowden, Hutchinson and Ross, Stroudsburg, 429 pp., U.S. $ 35.55. The philosophy behind the "Bench mark Papers in Geology" of collection, sifting and rediffusion of specialist scientific literature must be commended. The volume under review undoubtedly presents a well ordered collection of papers but in the end leaves one with a sense of disappointment, not with the inclusions, rather the omissions. The papers themselves are generally of a high standard and provide a useful chrono-
logical sequence which deals with many aspects of the problem of Loess f o r m a t i o n . However, as the expert editor states in his introduction "one could propose to divide the views on Loess into 'pedological' and 'geological' . . . the respective views are (of) the USSR and the United States". The introduction very properly exhorts workers in this field to reconcile the views of the theorists; it is therefore regrettable that the o p p o r t u n i t y to attain this objective presented by this compilation was not taken and pursued with greater vigor. For, as the editor acknowledges in his preface, the Russian literature is underrepresented in this volume. The papers which have been presented represent to a large extent the Western viewpoint and the editor brings the variety of opinions and aspects of this viewpoint clearly to the reader's attention, although he is reticent in passing his own opinion when he is comparing authors' opinions. The papers deal principally with the origin of the majority of the major Loess deposits found in the world with the notable exception of the Chinese and Russian deposits which receive minimal attention. Genesis, however, embraces not only origin but also subsequent secondary soil-forming processes including the f o r m a t i o n of secondary minerals and diagenic processes. It is conceivable that the inclusion of papers on physico-chemical aspects would t h r o w light on the problem of reconciling the t w o main theories of Loess formation. Although it has been indicated that the book lacks balance, nwvertheless the papers chosen present a broad view of those deposits which are the principal topic of discussion. They guide the reader in an able manner, through the history of opinion f r o m 1834 to 1973 with an emphasis on w o r k carried out since 1950. The subject index is full and comprehensive as is the authors' citation index. The mode of presentation, with the editor's specific comments preceding a distinctive set of papers ensures logical grouping and the book is well produced with a clear and fully documented list of contents. The figures are well and clearly presented and have been chosen carefully to complement the edited text. A minor blemish is in the