This book should be of great benefit to undergraduate and postgraduate students who are taking geology or geophysics courses. It is also aimed at a wider audience, those who need to know what exists below the surface and those to whom the state of that subsurface, and hence to a large extent our environmental well-being, is important. Geophysics is a science that transcends the usual disciplinary boundaries, so this book will also be beneficial for engineers, geologists, planners, archaeologists, hydrologists, geographers and environmental scientists. The layout of this second edition of the book follows that of the first edition to ensure continuity but is greatly enhanced by the addition of new case studies, figures and plates.