The Manx slate series, the ancient and complex bedrock of the Isle of Man, has been affected by three pre-Carboniferous phases of deformation. The oldest, designated F 1 , produced the large-scale Isle of Man syncline and acute folds with steep axial planes; F 2 refolded the earlier system with more open folds and axial planes with a gentle northwest dip; F 3 is a suite of open cross flexures, with axial planes dipping steeply east-northeast, developed on the flanks of previous structures. Distinct metamorphic textures characterize the F<1) and F<2) phases. The low-grade F<1) fabric was controlled by both flexural slip along bedding and planar slip parallel to axial planes of the folds. The F<2) fabric is characterized by the growth of porphyroblasts of leucoxene, muscovite, chloritoid, cordierite, garnet, biotite, and tourmaline along the hinge of the F<2) synform and it appears in an elongate belt in the middle of the island.