This book gives an up-to-date overview of the physical geology of sub-volcanic intrusions. Topics covered in this wide-ranging volume include important aspects of the field geology and physical volcanology of sills, laccoliths and sub-volcanic complexes, magma-sediment interaction and numerical and experimental studies aimed at quantifying more precisely the emplacement mechanics of high-level magmatic intrusions. Provocative papers ask whether laccoliths and high-level sills are forming today, and question the nature of the relationship between high-level intrusions and contemporaneous volcanic activity. Several contributions also deal with the more applied aspects of high-level magma emplacement and 3D seismic imaging of sill and laccolith complexes as relevant to the hydrocarbons industry. It is hoped that with the publication of this volume a consensus will emerge that will help to advance our understanding of the more important physical factors governing the emplacement of high-level intrusions in the continental crust, along with their wider geotectonic implications.