The Outer Hebrides are composed primarily of metamorphic gneisses and igneous rocks of Precambrian age, apart from a small area near the town of Stornoway in Lewis, which has rocks of either upper Palaeozoic or lower Mesozoic age resting unconformably on the Precambrian rocks.
The Outer Hebrides are composed primarily of metamorphic gneisses and igneous rocks of Precambrian age, apart from a small area near the town of Stornoway in Lewis, which has rocks of either upper Palaeozoic or lower Mesozoic age resting unconformably in a bad state.