Three tectono-sedimentary units having Caledonian tectono-thermal histories are recognized within the metamorphic rocks of the SW Ox Mountains Inlier. The different structural levels represented by each of these units were juxtaposed along tectonic contacts late in the individual tectono-thermal histories. The highest structural unit is the virtually unmetamorphosed, probably Southern Highland (Upper) Dalradian, Ardvarney Formation which can be related on a regional scale to the Donegal 'Tay Nappe' structure. The Raheen Barr succession probably ranges from the Islay to Easdale subgroups of the Middle Dalradian and can be correlated with the metamorphic rocks of the Nephin Beg succession in NW Co. Mayo. The Ox Mountains succession represents the deepest structural level seen and consists of basic volcanic rock, graphite schist, marble quartzite, psammite, and semi-pelite. It forms the envelope to the syn- to late kinematic 500 ± 18 Ma Ox Mountains Granodiorite and stratigraphically it can best be compared with the Appin and Argyll groups of the Dalradian of Connemara.
The differing tectono-thermal histories of the different structural levels in this part of the metamorphic Caledonides of western Ireland possibly reflect the diachronous nature of the deformation and metamorphism in the orogen. Interaction during juxtaposition must have involved movement related to more than one direction of tectonic transport.