Geology of the Country Around Pwllheli

The district described in this memoir (1:50 000 geological sheet 134) covers the central area of the Llyn Peninsula in north-west Wales. The solid rock types vary from deformed m'lange and Precambrian granites, through an array of Cambrian and Ordovician clastic sedimentary rocks, to a wide range of tholeitic to alkaline and ultrabasic to acid igneous rocks.