This book is the result of an international working group entitled 'Geology and Ecosystems' that was organized by the IUGS commission on Geological Sciences for Environmental Planning (COGEOENVIRONMENT). The aim of the working group is to increase awareness and build methodological principles of ecological geology as a new branch of science. This book includes the analysis of the relationship between the different geological, hydrochemical, hydrogeological, and engineering-geological processes and the processes within surface ecosystems. Modern engineering activity associated with the mining of minerals, excessive groundwater withdrawal, disposal of industrial and domestic liquid wastes (including radioactive wastes) and their impacts on all components of the environment are analyzed, as is the "water factor" impact on ecosystems. It is intended as a professional update for all scientists and professionals with an interest in the Earth's environments and environmental protection.