In summer 2015 a group of geologists, artists, ecologists, musicians and storytellers, aged 18 to 70-plus, embarked on a voyage of geological discovery around the Argyll islands on Leader, a Brixham sailing trawler. Their journey followed on from one in which Leader and her crew recreated part of Hugh Miller’s 1844 cruise of the Betsey around the Inner Hebrides. Elizabeth Pickett, geologist and illustrator, shares her diary and sketchbook. Here in part one of what will be a double-header, she describes the journey from Oban to Shuna.

View from Dunollie lighthouse.

Our voyage was named ‘Testimony of the Rocks’, in honour of Hugh Miller’s final book. Miller was fascinated by the natural world, writing, “Nature is a vast tablet, inscribed with signs, each of which has its own significance and becomes poetry in the mind when read”. He also wrote of his great interest in the close association of human history with geological science. So, with these themes and Miller’s inquiring spirit in mind, we set out to explore the beautiful Argyll islands and their interwoven stories of geology, landscape, natural history and people

20 June
Magmatic Mull

We meet Leader and our fellow voyagers at the North Pier in Oban. Our first destination, where we anchor for the night, is Loch Spelve, held in the curve of the ring-intrusions of Mull’s ancient volcano, and with the Great Glen Fault passing deep below. The dark igneous rocks that mass above us and disappear into cloud are transformed into arcs of pink, red and green on the beautiful geological map of Mull. We discuss charts and forecasts with our skipper Lara, and out of this emerges a more detailed plan for our voyage. We are to head south from Mull, bound for islands of far older quartzite and slate. These metamorphic rocks are part of the ‘Dalradian’, a group of rocks 750 to 550 million years old and named after the ancient Scots kingdom of Dalriada.

From our anchorage in Loch Spelve.

21 June
Rocks of Dalriada

Islands slide past as we head south into the Sound of Luing. The sea is silk-smooth and we glimpse porpoises. At Kinuachdrachd Pier on Jura we learn more about Dalradian rocks and the geological events they record. Originally sediments and lavas in long-vanished seas, they were later metamorphosed during Caledonian mountain-building to become slate, quartzite, marble and schist. To the sound of a cuckoo we explore a shoreline of Jura slate. The coast is bright with the pinks of thrift, ragged robin and foxgloves, and the yellow of bird’s-foot trefoil and tormentil. The geological map of Jura is mainly yellow too – representing a great thickness of Jura quartzite.

Leader seen from Jura

22 June
Metalimestone and music

On the west coast of Shuna we look at geological maps spread out on the shingle. Shuna stands out with its stripe of bright blue. This is the Degnish Limestone and we examine a nearby outcrop. Intriguing textures provide clues to its origins in a warm shallow sea and later alteration to become the cleaved metalimestone, or marble, we see today. Orchids thrive in this lime-rich spot. Islanders used the limestone too – there’s a ruined limekiln nearby. Walking across the island we peer through rhododendrons at the crumbling concrete castle of Shuna House, and admire swirling patterns in sea-worn Craignish Phyllite. In evening sunlight in Arduaine there’s singing and guitar music on deck.

Limekiln on Shuna

To be continued…

The voyage was run by the Scottish Geodiversity Forum, the Isle of Luing Community Trust and the Friends of Hugh Miller. If you’d like to find out more about the voyage or Hugh Miller see Emma MacLachlan’s film, Hugh’s News 26 in: www.thefriendsofhughmiller.org.uk and www.atlanticislandscentre.com