The Small Isles
Na h-Eileanan Tarsainn
The dramatic ‘Small Isles’ of Canna, Eigg, Muck and Rum in the far west of Lochaber have a fiery past that tells us of a time when active volcanoes dominated the north-west coast of Scotland. The islands can be reached by ferry from Mallaig all year and from Arisaig during the summer.
The Small Isles are home to a fascinating variety of rocks, ranging from the 3-billion years old Lewisian Gneiss, to the remains of volcanoes which erupted around 60 million years ago.
Canna, Eigg and Muck are made up of almost exclusively of volcanic rocks. These were erupted 60-65 million years ago when things started to get volcanically violent!
The stopping points on the geotrail help to explain the forces that have created the distinct features of the Small Isles.
1. Rum Volcano – Bholcàno Rùma
From the ferry you’ll enjoy excellent views of the Small Isles. Look out for the sight of the high Rum Cuillin towering over the other Small Isles. These mountains are the eroded roots of an ancient volcano that started life as a huge dome around 2,000 metres high.
2a Rum: Shoreline Sandstone – Rùm: Clachan-Gainmhich Cladaich
Walk along the road from the landing stage towards Kinloch Castle and have a closer look at the rocks on the shoreline. These are 1,000 million year old Torridonian sandstones.
2b Coire Dubh
Follow the path uphill from Kinloch Castle towards Coire Dubh. This is the main path up the mountain of Hallival and is signposted ‘Rum Cuillin’. After about 1km the rock you’re walking on will change from Torridonian sandstone to breccia – a rock made of angular fragments of Torridonian sandstone and gneiss. This rock was formed inside a volcano, when the dome created above a magma chamber began to fracture and collapse.
3. Canna – Canaigh
As you journey towards Canna, you’ll notice that there is a flat platform of rock about 30 or 40 metres above sea level around the coast of Rum. This goes round most of the island and was cut about 100,000 years ago before the last glacial ice cover, when the sea level was much higher than it is today. When the last glaciers melted and the weight of the ice was removed, the Earth’s crust ‘bounced back’ – making it higher than it was before. This effect created what are known as ‘raised shorelines’. You’ll see similar raised shorelines around the other Small Isles and at Arisaig.
Canna is the furthest of the Small Isles from the mainland. It is mostly made up of basalt lava flows. On the north-east tip of the island sits Compass Hill. It’s called this because iron in the hill’s basalt rocks affects compasses up to 3 miles away!
4. Sgurr of Eigg – Sgùrr Eige
Like Canna, Eigg is largely made up of basalt lava flows. Rivers flowing across the basalt lava plateau eroded deep channels over time. It sounds strange but the prominent peak of An Sgurr actually marks the location of one of these river valleys. During one of the last volcanic eruptions, thick lava flowed along a river valley and cooled to form a rock called pitchstone. This lava is much harder than the surrounding basalt and while the rock of the valley sides has worn away, the lava that once filled it now stands out as a great prow.
5. Eigg: Singing Sands – Eige: Gainmheach Sheirmeach
You’ll need to stay a while to visit the famous ‘singing sands’ of Eigg as they’re at the north end of the island, but you may be able to save yourself a long walk by hiring a mountain bike or taxi at the pier. The ‘singing sands’ consist of pure quartz grains from the Jurassic rock outcrops around the north end of the island. If you walk on the sand in dry weather, the texture creates a shrill ‘singing’ squeak.
Eigg is also a place of famous discoveries - the Victorian geologist Hugh Miller unearthed the fossilised remains of Jurassic sea turtles, a crocodile and a plesiosaur in the island’s rocks.
6. Muck – Eilean Nan Muc
Muck is the smallest and flattest of the Small Isles, and is a great place for a pleasant walk. Take a 1km walk from the landing stage across the island to an enclosed beach on the north coast. You’ll see lava flows exposed on the shoreline around you. These probably came from a volcano on Mull. When magma erupts it cools much more quickly than it does inside a magma chamber, so there is very little time for crystals to form. Take a close look at the basalt around the bay and you’ll see that the crystals in it are tiny.