Principles of Rock Deformation: (2 Petrology and Structural Geology)

Physicists attempt to reduce natural phenomena to their essential dimensions by means of simplification and approximation and to account for them by defining natural laws. Paradoxically, whilst there is a critical need in geology to reduce the overwhelming field information to its essentials, it often re­ mains in an over-descriptive state. This prudent attitude of geologists is dictated by the nature of the subjects being consi­ dered, as it is often difficult to derive the significant parame­ ters from the raw data. It also follows from the way that geolo­ gical work is carried out. Geologists proceed, as in a police investigation, by trying to reconstruct past conditions and events from an analysis of the features preserved in rocks. In physics all knowledge is based on experiment but in the Earth Sciences experimental evidence is of very limited scope and is difficult to interpret. The geologist's cautious approach in accepting evidence gained by modelling and quantification is sometimes questionable when it is taken too far. It shuts out potentially fruitful lines of advance; for instance when refu­ sing order of magnitude calculations, it risks being drowned in anthropomorphic speculation. Happily nowadays, many more studies tend to separate and order the significant facts and are carried out with numerical constraints, which although they are approxi­ mate in nature, limit the range of hypotheses and thus give rise to new models.

Table of Contents:
1. Introduction.- 2. Strain and Stress.- 2.1. Strain.- 2.2. Elements of Rheology.- 2.3. Stress.- 2.4. Progressive Strain.- 2.5. Stress-Strain Relations.- For Further Reading.- 3. Theory of Discontinuous Deformation.- 3.1. Introduction.- 3.2. Fracture Modes and Relationship to Stress.- 3.3. The Brittle-Ductile Transition.- For Further Reading.- 4. Mechanisms of Continuous Deformation.- 4.1. Introduction.- 4.2. Plastic Deformation in the Solid State.- 4.3. Fluid Assisted Deformation.- For Further Reading.- 5. Discontinuous Deformation: Structures, Interpretations.- 5.1. Introduction.- 5.2. Joints.- 5.3. Tension Fractures.- 5.4. Stylolitic Joints.- 5.5. Faults.- For Further Reading.- 6. Structures Caused by Homogeneous Deformation.- 6.1. Introduction.- 6.2. Planar Structures.- 6.3. Lineations.- For Further Reading.- 7. Interpretation of Continuous Homogeneous Deformation Structures.- 7.1. Introduction.- 7.2. Mechanisms Responsible for the Development of Structures.- 7.3. Interpretation of Structure Resulting from Viscous Flow.- 7.5. Interpretation of Intracrystalline Plastic Deformation Structures.- For Further Reading.- 8. Continuous Heterogeneous Deformation: Typical Structures.- 8.1. Introduction.- 8.2. Microstructures.- 8.3. Shear Zone.- 8.4. Stretch Structures; Boudinage.- For Further Reading.- 9. Folds.- 9.1. Introduction.- 9.2. Geometrical Analysis of Folds — The Case of an Isolated Surface.- 9.3. Folding of an Isolated Bed.- 9.4. Folding of a Stratified Sequence.- 9.5. Relationship of Folds to the Strain Axes.- 9.6. Superposed Folds.- For Further Reading.- Appendix I. Tensorial Analysis of Strain and Stress.- I.1. Strain.- I.1.1. Tensorial analysis.- I.1.2. Typical strain regimes.- I.2. Stress.- I.2.1. Tensorial analysis.- I.2.2. Typical stress regimes.- I.3.Elastic Deformation.- Appendix II. Measurement of Finite Strain.- II. 1. Introduction.- II.2. Definitions.- II.2.1. Strain of a linear marker.- II.2.2. Strain in simple shear.- II.2.3. Strain ellipsoid.- II.2.4. Strain ellipse.- II.2.5. Mohr circle of strain.- II.3. Determination of the Strain Ellipse.- II.3.1. Measurement of elongation.- II.3.2. Measurement of shear strain.- II.3.3. Deformed elliptical objects.- II.3.4. Variations in the distribution of point markers.- II.4. Determination of the Strain Ellipsoid.- II.4.1. Measurement of ellipses.- II.4.2. Reorientation of plano-linear markers.- II.4.3. Deformation of mineral veins.- II.5. Strain in Simple Shear.- II.5.1. Shear plane/foliation obliquity.- II.5.2. Rotation of planar markers.- II.5.3. Rotation of microstructural markers.- Appendix III. Cyclospherical Projections and Figures.- III.1. Introduction.- III.2. Definitions.- III.3. Representation of Straight Lines and Planes.- III.4. Density Diagrams.- III.5. Analysis of Density Diagrams.- For Further Reading.

Review :
'The international standing of the author and the clarity of his explanation and illustration make the book a worthwhile addition to libraries worldwide.' Geological Magazine (about the French edition) '... it will prove valuable not only in undergraduate structural geology courses, but also to the interested non-specialist. The book is well illustrated with abundant line diagrams.' Geophysical Journal of the Royal Astronomical Society