The Precambrian basement of England and Wales is exposed within a number of inliers, which are regarded as `windows' into the cover strata. The rocks that are revealed are of considerable geological diversity and have long been the focus of scientific research and educational interest. The featured GCR sites in this book are intended to show the broad spectrum of lithologies and geological processes representative of each formed terrane of rock. Consequently, the volume includes accounts of: Volcanic sequences formed in a variety of tectonic settings; Plutonic igneous complexes; Sedimentary and volcaniclastic strata ranging from deep-water marine to terrestrial environments; Low-to high-pressure metamorphic rocks; and Intricate deformational structures.