Coll and Tiree - Their Prehistoric Forts, and Ecclesiastical Antiquities, With Notices of Ancient Remains in the Treshnish Isles #234021

The chronology of the Duns is more complicated, and, as regards the Hebrides, the only tenable conclusion appears to be that while they are prehistoric in origin, the period of their erection cannot be placed later than the ninth to the thirteenth century, some of them probably dating back even so far as the Christian era — or beyond it. The true Brochs (of Glenelg, Lewis, Caithness.