The geology of the map sheet 6, Aston, is described. The stratigraphic sequence consists of Paleozoic rocks from Cambro-Ordovician to Carboniferous age and some Cretaceous rocks along the northern border of the axial zone. The lower part of the Cambro-Ordovician is strongly metamorphosed and consists of micaschists, migmatites and granites. A leucocratic augengneiss, probably an orthogneiss, forms the core of the Aston-Hospitalet massif. Two intrusive granites occur in the Paleozoic rocks. Two types of major structures are distinguished, the metamorphic infrastructure and the non-metamorphic suprastructure. Several phases of deformation, all belonging to the Hercynian orogeny have been recognized. The relationships of the metamorphism to these deformation phases and the metamorphic events of the orthogneisses are described.