This combined textbook and reference manual introduces key topics and techniques in gravity and magnetic exploration, with practical online resources. Preface; Objectives of this book; Related books; Organization of this book; Study questions and exercises; Units; Acknowledgements; 1 Introduction; 1.1 Overview; 1.2 The Earth and its planetary force fields; 1.3 Basis of the gravity and magnetic methods; 1.3.1 Gravity; 1.3.2 Magnetics; 1.4 Foundations of geophysical methods; 1.5 Geophysical practices; 1.5.1 Planning phase; 1.5.2 Data acquisition phase; 1.5.3 Data processing phase; 1.5.4 Interpretation phase; 1.6 Nature of geophysical data; 1.6.1 Data documentation; 1.6.2 Data errors; 1.7 Key concepts; Part I Gravity exploration 2 The gravity method2.1 Overview; 2.2 Role of the gravity method; 2.3 The Earth's gravity field; 2.3.1 Gravitational force; 2.3.2 Gravity units; 2.3.3 Basis of the gravity method; 2.3.4 Spatial variations; 2.3.5 Temporal variations; 2.3.6 Measurement; 2.4 History of the gravity method; 2.5 Implementing the gravity method; 2.5.1 Planning phase; 2.5.2 Data acquisition phase; 2.5.3 Data processing phase; 2.5.4 Interpretation phase; 2.5.5 Reporting phase; 2.6 Key concepts; 3 Gravity potential theory; 3.1 Overview; 3.2 Introduction; 3.3 Gravity effects of a point mass 3.4 Gravity effects of an extended body3.5 Idealized source gravity modeling; 3.6 General source gravity modeling; 3.6.1 Generic 2D modeling procedures; 3.6.2 Generic 3D modeling procedures; 3.6.3 Least-squares 3D modeling; 3.6.4 Least-squares 2D modeling; 3.6.5 Least-squares modeling accuracy; 3.6.6 Least-squares modeling in spherical coordinates; 3.7 Gauss' law; 3.8 Gravity anomaly ambiguity; 3.9 Poisson's theorem; 3.10 Pseudoanomalies; 3.11 Key concepts; 4 Density of Earth materials; 4.1 Overview; 4.2 Introduction; 4.3 Types of densities; 4.3.1 True density; 4.3.2 Bulk density 4.3.3 Natural density4.4 Density of the Earth's interior; 4.5 Rock densities; 4.5.1 Lithology; 4.5.2 Lithostatic pressure and void space; 4.5.3 Temperature; 4.5.4 Summary; 4.6 Density measurements; 4.6.1 Laboratory measurements; 4.6.2 Gravity measurements; 4.6.3 Correlative property measurements; 4.7 Density tabulations; 4.8 Key concepts; 5 Gravity data acquisition; 5.1 Overview; 5.2 Introduction; 5.3 Measuring gravity; 5.3.1 Land surface measurements; 5.3.2 Moving platform measurements; 5.3.3 Gravity gradiometry; 5.3.4 Absolute gravity; 5.3.5 Navigation control; 5.4 Gravity surveying 5.4.1 Survey design5.4.2 Survey procedures; 5.5 Gravity measurements from space; 5.5.1 Passive measurements; 5.5.2 Active measurements; 5.5.3 Satellite gravity mapping progress; 5.6 Key concepts; 6 Gravity data processing; 6.1 Overview; 6.2 Introduction; 6.3 Extraneous gravity variations; 6.3.1 Temporal variations; 6.3.2 Datums; 6.3.3 Latitude variation; 6.3.4 Atmospheric mass correction; 6.3.5 Height effect; 6.3.6 Mass effect; 6.3.7 Terrain effect; 6.3.8 Miscellaneous effects; 6.4 Gravity anomalies; 6.4.1 Fundamental elements; 6.4.2 Classes of gravity anomalies