The Islands of the Hebridean Igneous Province: Skye, Mull, Rùm and Arran

The islands of the Hebridean Igneous Province are largely composed of Palaeogene igneous rocks relating to extensional tectonics and magmatic activity within the interval ~62–55 Ma. Their geology is dominated by plateau lavas, subvolcanic central igneous complexes, and sills and dyke swarms intruded into earlier sedimentary and metasedimentary rocks. Modification of the igneous terrain by successive Pleistocene ice sheets and mountain glaciers has produced radiating troughs and cirques, pinnacled aretes and glaciated trap topography. During the local Last Glacial Maximum (~30–26 ka), Skye, Mull and Arran sustained independent ice centres that fed ice streams on the adjacent shelves; following decoupling from these ice streams, locally nourished glaciers readvanced on Skye and Arran. During the Loch Lomond Stade (~12.9–11.7 ka) all four islands hosted mountain glaciers that deposited end, lateral and recessional moraines. Postglacial landforms include periglacial and aeolian landforms on high ground, and spectacular landslides (one of which is the largest in Britain) at sites where failure of sedimentary rocks has caused extensive collapse of the overlying lavas. A wide range of coastal features are represented, including shore platforms of various ages, raised deltas, raised shingle ridges and both Lateglacial and Holocene raised beaches. The islands of the Hebridean Igneous Province are internationally renowned not only for their outstanding geodiversity, but also the haunting beauty of their strikingly dramatic landscapes.