Skye

Landscape Fashioned by Geology

• Introduction
• Setting the Scene
• The Ancient Rocks
• The Younger Rocks
• The Lava Plateau
• The Roots of Volcanoes
• Altered Rocks
• The Changing Climate
• Landslides
• Beaches

Beaches

Modern beaches

Sandy beaches are not common on Skye because sandy sediment sources are scarce, the coast shelve too steeply, and wave energy is quickly dissipated along the long, deep sea lochs that are a feature of Skye's indented coastline. Most of the beaches are derived from glacial deposits; for example, many cobbles on the beach of Sleat have been carried from the mainland.

The dazzling creamy-white beaches known locally as coral sands are created by the calcareous alga Lithothamnion, which has a remarkable resemblance to branching coral and which flourishes in sheltered bays around the west coast. Broken fragments are continuously washed up and these unusual sands were used locally to 'lime' acid, peaty soils.

Ancient beaches and past changes of sea level

Benches and notches carved into the cliffs of northern and western Skye bear witness to relentless attrition by the sea over many thousands of years, adding to the splendour and mystery of this rugged coastline. These 'wave-cut platforms', some still capped by beach shingle, are a stark reminder that the sea was once as much as 30 metres higher than it is today. The platforms were created at various times over the past 500,000 years, during glacial periods when the earth's crust sagged under the enormous weight of ice sheets.

During these periods the sea level rose in Scotland, even though the world's oceans were partly locked up in great continental ice sheets and sea level at the equator was actually 100 metres or more lower than today.

Two distinct sets of raised beaches occur on Skye. Those lying 15 to 30 metres above sea level formed as Scotland's last widespread ice sheet decayed, about 15,000 years ago. A delta and raised beach that formed at this time provide a valuable source of sand and gravel near Kyleakin. The other set of raised beaches formed between 8,000 and 6,500 years ago during a period of rapid rise in world sea level caused by the melting of ice sheets in North America and Scandanavia and before Scotland had completely recovered from the unloading of its former ice cover. These raised beached occur up to 10 metres above present sea level; some are associated with longabandonned caves, geos and sea stacks and at Braes, 12 kilometres south of Port Righ, the coast is linked to an island by an unusual gravel spit (a 'raised tombolo'). The raised beaches all tilt gently towards the west owing to varying uplift since deglaciation.