Geodynamics is an old science. Most of the basic theories have been conceived in principle during the 19th century and not many fundamen­ tal ideas have been added since. Some progress has been made in the following-up of these concepts and, in some instances, in the deter­ mination of some important facts about the Earth. Nevertheless, geo­ dynamics has been a highly speculative subject for about a hundred years and it is not likely that this situation will change during the next hundred. It is also unlikely that many basic new ideas will be added in that time interval. The reason for this lies in the extreme difficulty of obtaining really relevant data about the mechanics of the Earth, partly due to the impossibility of probing into the depths of the Earth by direct means to any considerable extent and partly due to the fact that the time intervals in which . . something happens" are of the order of millions of years, which is much too long for any human being to wait and ex­ periment with. The situation in geodynamics is, therefore much akin to that which existed when the ancient Greek philosophers were speculating about the possibly atomic structure of matter: there was, at that time, absolutely no hope to either confirm or to reject the hypothesis.

I. Physiographic and Geological Data Regarding the Earth.- 1.1. Introduction.- 1.2. Geological Evolution.- 1.21. The Basic Rock Types.- 1.22. Geological Time Scale.- 1.23. Paleoclimatic Data.- 1.3. Geography of Continents and Oceans.- 1.31. Geometrical Arrangement.- 1.32. The Hypsometric Curve.- 1.4. Physiography of Orogenetic Systems.- 1.41. General Features.- 1.42. Mountain Ranges.- 1.43. Systems of Mountain Ranges.- 1.44. Mid-Ocean Ridges.- 1.45. Shear Patterns.- 1.5. Physiography of Faults and Folds.- 1.51. Faults.- 1.52. Folds.- 1.6. Physiography of Other Features.- 1.61. Meteor Craters.- 1.62. Boudinage.- 1.63. Domes.- 1.64. Volcanoes.- 1.65. The Upheaval of Land in Fennoscandia.- II. Geophysical Data Regarding the Earth.- 2.1. Gravity Data.- 2.11. Gravity and Gravity Anomalies.- 2.12. Distribution of Gravity Anomalies. Isostasy.- 2.2. Seismological Data.- 2.21. Earthquakes and Seismic Waves.- 2.22. Seismicity Studies.- 2.23. Magnitude Studies.- 2.24. Fault Plane Studies.- 2.3. The Layering of the Earth.- 2.31. Crustal Studies.- 2.32. The Interior of the Earth.- 2.4. Data from Age Determinations.- 2.41. Principles.- 2.42. An Extended Geological Time Scale.- 2.5. Thermal Data.- 2.51. Surface Heat Flow Measurements.- 2.52. Temperature in the Earth's Interior.- 2.53. Thermal History of the Earth.- 2.6. Data from Magnetization of Rocks.- 2.61. Principles.- 2.62. Results.- 2.7. Geochemical Data.- 2.71. Geochemistry of the Interior of the Earth.- 2.72. Geochemistry of the Crust.- III. The Mechanics of Deformation.- 3.1. Finite Strain in Rheological Bodies.- 3.11. The Physics of Deformation.- 3.12. The Structure of a Finite Strain Theory.- 3.13. The Possible Schemes of Dynamics.- 3.14. Additional Stress and Strain.- 3.2. Elasticity and Plasticity.- 3.21. Infinitesimal Elasticity Theory.- 3.22. Dislocations.- 3.23. Plasticity.- 3.3. Hydrodynamics of Viscous Fluids.- 3.31. Fluid Kinematics.- 3.32. Dynamics of Viscous Fluids.- 3.33. Thermohydrodynamics of Viscous Fluids.- 3.4. Other Types of Rheological Behavior.- 3.41. Principles.- 3.42. Maxwell Liquid.- 3.43. Kelvin Solid.- 3.44. Heat Convection in General Rheology.- 3.5. Discontinuous Displacements.- 3.51. The Physics of Fracture.- 3.52. Phenomenological Theories.- 3.53. Microscopic Theories.- 3.54. Analytical Attempts.- 3.6. Rheology of the Earth: The Basic Problem of Geodynamics.- 3.61. General Considerations.- 3.62. Stresses of Short Duration.- 3.63. Stresses of Intermediate Duration.- 3.64. Stresses of Long Duration.- 3.65. Summary.- IV. Effects of the Rotation of the Earth.- 4.1. The Figure of the Earth.- 4.11. The Ellipticity of the Earth.- 4.12. The Equilibrium Figure of the Earth.- 4.2. The Polfluchtkraft.- 4.21. Concept of the Polfluchtkraft.- 4.22. Ertel's Theory.- 4.23. Criticisms.- 4.3. The Question of Stability of the Earth's Axis of Rotation.- 4.31. The Problem.- 4.32. Effects of Circulations on a Rigid Earth.- 4.33. Polar Wandering in a Yielding Earth.- 4.4. Other Effects of the Earth's Rotation.- 4.41. Tidal Forces.- 4.42. Coriolis Force.- V. Continents and Oceans.- 5.1. Primeval History of the Earth.- 5.11. The Problem of Continents and Oceans.- 5.12. The Origin of the Earth.- 5.13. The Earth's Early Thermal History.- 5.14. The Birth of the Moon.- 5.2. Evolution and Growth of Primeval Continents.- 5.21. The Hypothesis of Laurasia and Gondwanaland.- 5.22. The Notion of Continental Drift.- 5.23. Continental Spreading.- 5.24. Volcanic Growth of Continents.- 5.3. Primeval Convection.- 5.31. The Formation of Continents by Convection.- 5.32. Physical Aspects of Convection Currents.- 5.33. Analytical Theory.- 5.4. Tetrahedral Shrinkage.- 5.41. Principles.- 5.42. Criticism.- 5.5. Formation of Continents by Expansion.- 5.51. Thermal Theories.- 5.52. Cosmological Speculations.- 5.6. Evaluation of Theories of Continents and Oceans.- VI. Orogenesis.- 6.1. Fundamentals.- 6.11. Crustal Shortening.- 6.12. A Basic Geodynamic Relationship.- 6.2. The Contraction Hypothesis.- 6.21. Principles.- 6.22. The Existence of a Level of No Strain.- 6.23. The Thickness of the Earth's Crust and Mountain Building.- 6.24. The Junctions of Island Arcs.- 6.25. The Extension Factor.- 6.26. Compatibility with Seismic Data.- 6.3. Continental Drift Theory.- 6.31. Principles.- 6.32. Extension Factor. Transcurrent Faulting.- 6.33. Origin of the Forces Causing Drifting.- 6.4. Convection Current Hypothesis of Orogenesis.- 6.41. General Principles.- 6.42. Steady-State Convection.- 6.43. Intermittent Convection Currents.- 6.44. Roller Cell Theory.- 6.5. The Hypothesis of Zonal Rotation.- 6.51. Principles.- 6.52. The Origin of the Atlantic Ocean.- 6.53. Persistence of Zonal Rotation.- 6.6. Undation Theory.- 6.61. Principles.- 6.62. Forces in the Undation Theory.- 6.63. Secondary Orogenesis.- 6.7. Expansion Hypothesis of Orogenesis.- 6.71. Principal Outlines.- 6.72. Matschinski's Buckling Theory.- 6.73. Expansion by Rock Metamorphism.- 6.8. Orogenesis and the Rotation of the Earth.- 6.81. The Problem.- 6.82. General Theory.- 6.83. The Elastic Model.- 6.84. Model of a Weak Earth.- 6.85. Tectonic Significance.- 6.9. Evaluation of Theories of Orogenesis.- VII. Dynamics of Faulting and Folding.- 7.1. Dynamics of Faulting.- 7.11. Principles.- 7.12. Anderson's Theory.- 7.13. Analytical Theories.- 7.2. Theory of Earthquakes.- 7.21. Requirements of a Theory of Earthquakes.- 7.22. Mechanism of Stress Creation.- 7.23. Models of Earthquake Foci.- 7.24. The Friction at an Earthquake Fault.- 7.25. Fracture Theories of Earthquakes.- 7.3. Analytical Theories of Folding.- 7.31. The Problem of Folding.- 7.32. Buckling.- 7.33. Theories Assuming Infinitely Flexible Strata.- 7.34. General Rheology.- 7.4. Model Experiments of Faults and Folds.- 7.41. Theory of Scale Models.- 7.42. Faults.- 7.43. Folds.- 7.5. Theory of Systems of Faults and Folds.- 7.51. The Problem.- 7.52. Fracture Systems.- 7.53. Folding Systems Originated by Buckling.- 7.54. Plastic Folding.- 7.55. General Rheology.- 7.56. Rift Systems.- 7.6. Evaluation of Theories of Faults and Folds.- VIII. Dynamics of Other Features.- 8.1. Meteor Craters.- 8.11. Physical Principles.- 8.12. Correlations.- 8.13. Liquid-Drop Model of Crater Formation.- 8.14. Analogy with Explosion Craters.- 8.2. Boudinage.- 8.21. Experimental Approach.- 8.22. Theoretical Approach.- 8.23. Tectonic Lenses.- 8.3. Domes.- 8.31. Principles of a Theory of Domes.- 8.32. Analytical Attempts.- 8.33. Model Studies of Domes.- 8.4. Volcanism.- 8.41. The Shape of Volcanoes.- 8.42. Volcanic Heat and Orogenesis.- 8.43. Mechanism.- 8.5. Postglacial Uplift.- 8.51. General Remarks.- 8.52. The Haskell Theory.- 8.53. Postglacial Uplift Interpret…