[2][3] The basin fill comprises fluvial Old Red Sandstone (ORS) magnafacies[4][5][6] with minor silicic volcanic[7] and mafic sub-volcanic[8] centres.
The depocentre of the basin is located between the MacGillycuddy's Reeks and the Kenmare River on the Iveragh peninsula where the succession is at least ca.
[9] During the Late Palaeozoic Variscan (or Hercynian) orogeny the deposits in the basin were subjected to compressional deformation that resulted in pressure solution cleavage formation, buckle folding and contractional faulting[10][11] under very low-grade metamorphic conditions.
[13] In combination, this corresponds to a late Givetian chronostratigraphic age on recent Devonian time scales.
[14] The general Late Devonian age of the basin fill is also given by miospore[15][16] and fish fossil records.