Layer upon layer of basalt lava flow, totalling up to 700 metres in depth were laid down during the Paleogene but these heavy, deep rocky deposits sat upon older rocks, sedimentary Jurassic clays, shales, limestones and sandstones.
These, weaker rocks cannot support the weight of the dense basalt above and over millions of years have slipped and slided to form the long ridge that we see today.
This North Atlantic Tertiary Volcanic Province also covered parts of Ireland, the Antrim Plateau and the famous Giant’s Causeway having been created at the same time. And indeed, on the Antrim Coast, thick layers of basalt overlay sedimentary rocks such as chalk.
After the end of the last ice age approximately 12,000 years ago the thick layers of ice that dominated the landscape melted and the underlying landscape rebounded, much as if you sit on a cushion and get up, the cushion will rebound to its non-compressed position. This rebounding caused significant movements in the geology of the area and contributed to the landslide and landslip landscape we see today.
The landslips were not cataclysmic but occurred slowly, often as post-glacial rebound and ice meltwaters caused landscape changes; at least one section dates to as recently as 6,000 years ago.
190 to 150 million years ago, during the Jurassic, the area was a lagoon, delta and shallow marine environment leading to deposition of shales, clays and limestone rocks. These sedimentary layers form the foundation under which the Trotternish ridge sits.
Approximately 60 to 50 million years ago the area was at the centre of major volcanic activity. This period saw the eruption of vast quantities of lava, primarily from fissures rather than central volcanoes, which spread across the pre-existing landscape, burying the Jurassic sedimentary rocks. These extensive sequences of flood basalts, known collectively as the Skye Lava Group , formed a thick volcanic plateau covering most of northern Skye.
Today the area is considered stable with only small movements detected.
And I’m sure you will agree it has created a beautiful landscape, surely one of the best in Scotland, if not the world.
