Finding viable solutions to many of the problems threatening our environment hinges on understanding the rocks below the Earth's surface. This volume has been designed for those evaluating the relative hazards of radioactive waste sites, investigating energy resources such as oil, gas and hydrothermal energy, studying the behaviour of natural hazards like earthquakes and volcanoes, or charting the flow of groundwater through the Earth. Treating the nature and behaviour of rocks in a detailed but accessible manner, the text first discusses the physical properties of rocks, proceeding by chapter through mechanical, fluid flow, acoustical, electrical, dielectric, thermal and magnetic properties. It then provides the theoretical framework for achieving reliable data and making reasonable inferences about the aggregate system within the Earth. It covers the important and most current theoretical approaches to the physics of inhomogeneous media, including theoretical bounds on properties, various effective medium theories, percolation and fractals.