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Contents 1 ENERGY SINKS Heat Flow, 2 Volcanic Heat, 4 Metamorphic Heat, 5 Strain Energy; Earthquakes, 7 Potential Energy; Uplift of Mountains, 8 Plate Tectonics, 8 Kinetic Energy of Rotation, 11 Summary, 13 2 ENERGY SOURCES Original Heat, 15 Gravitational Energy, 18 Core Formation, 19 Tidal Friction, 21 Radiogenic Heat, 23 Crustal Heat Versus Mantle Heat, 26 Summary, 28 3 TEMPERATURES WITHIN THE EARTH The Upper Mantle, 31 The Low-Velocity Zone, 31; Geotherms from Nodules in Kimberlite, 33 1 15 29

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vi Contents The Mantle's Transition Zones, 35 The Lower Mantle, 36 Layer D', 36; Layer D", 44 The Outer Core, 49 Composition of the Core, 49; Temperature from an Equation of State The Adiabatic Gradient, 54 , 52; The Temperature at the Inner Core-Outer Core Boundary, 56 The Melting Point of Iron, 56; Melting in the Fe-S System, 60 Summary, 65 4 DYNAMICS OF THE CORE Stability of the Core, 68 Causes for Convection, 70 Energy Requirements of the Geomagnetic Dynamo, 70 Efficiency of a Steady-State Thermal Dynamo, 75 An Improved Estimate of Efficiency, 78 The Entropy Balance Equation, 83 The Gravitational Dynamo, 88 Gravitational Energy, 89; Volumetric Relations, 91; Heat Output of Core, 95 5 CORE-MANTLE INTERACTIONS Efficiency of the Mantle, 100 Convection Patterns in the Mantle, 104 67 100 Convective Pattern for Distributed Sources of Heat, 104; Heat from the Core, 110 Additional Factors in Controlling the Flow, 112 Temperature Dependence of Physical Properties, 112; The Von Zeipel Insta- bility, 112; Ejects of Surface Plates, 114; Effects of Phase Transitions in the Mantle, 114 Influence of the Core on Convection in the Mantle, 118 Influence of the Mantle on Convection in the Core, 120 Some Final Remarks, 121 REFERENCES AUTHOR INDEX SUBJECT INDEX 125 133 137

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Energeticsf the Early

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