Note CXV — Chapter V
P. W. (Patrick Weston) Joyce translation
] Tonn Toma, the wave of Toma (a woman). The word Tonn (a wave or billow) was often applied to the sea-waves that break over certain sandbanks and rocks with an exceptionally loud roaring. Tonn Toma is the name of a sandbank at the head of Dingle Bay, just outside the extreme point of Rossbehy peninsula; and in the winter storms, the sea thunders on this sandbank, and indeed on the whole length of the beach of the peninsula, so as often to be heard twenty miles inland. This roaring is popularly believed to predict rain.
There is a chain of three hills, Stookaniller, Knockatinna, and Knockboy, lying between Behy bridge on the east and Drung mountain on the west, and isolated from the hills to the south-east by the valley of Glanbehy. These hills rise directly over Tonn Toma; and the old Gaelic name, Currach-Cinn-Adhmuid (the moor of the head [or hill] of timber) must have been anciently applied to one or all of them.
(See, for an account of the great historical tonns of Ireland, the author's "Origin and History of Irish Names of Places," series ii. page 251.)