There’s a saying on the Isle of Mull – “If you come to Mull the once you return again for sure” – and it’s not an idle boast, as those who have visited and subsequently revisited this ‘geological Mecca’ will agree. Second largest of the Inner Hebrides, Mull is famous for its Tertiary igneous geology – 6,000 feet of basalt lavas intruded by a complex of concentric bodies, ringed about three igneous centres. With its unique ring dyke of mixed acid and basic magma, Tertiary granites yielding Lewisian dates, and magnetic reversals in the lavas that make compass bearings untrustworthy, Mull is an enigmatic venue for geologists. The island’s best-known fossils are plant remains, including Ginkgo, Platinus, Corylites and Quercus, all preserved in Tertiary lake sediments deposited between lava flows. Once over collected, fossils from the famous Leaf Beds at Ardtun are now protected, as the site is an SSSI. But the biggest and most noteworthy fossil is ‘Macculloch’s Tree’. Remotely situated opposite Ardtun, on the tip of the Ardmeanach peninsula, it is a phenomenon that, if you visit Mull, you really should see.
I first came across Mull’s fossil tree as a geology student in 1966. Its location was pointed out while I was in the Ardtun Leaf Beds gully, so I scrambled over slippery rocks, past hexagonal columns of basalt and down to the shore to see. The panorama I beheld took my breath away. The view spread out in front of me, from the northern tip of Iona, across white-crested waves to the Isle of Staffa and the Treshnish Isles, and round to Loch Scridain where layer upon layer of basalt lava, like a giant wedding cake, topped the lowest flow in which the tree stood. Atlantic rollers broke against an islet and grey seals watched me from the waves. I drank it all in and, entranced by the beauty, Mull worked its magic on me. A small white cottage further east caught my eye in the bright spring sunshine. Little did I know that one day the occupant of that lonely cottage would become a friend or that I’d write about an intriguing history that had played out within that spellbinding view.
True to Mull’s saying, four years later I returned to discover more about the island’s geological past. However, it wasn’t until 1971 that I walked the seven milesthe old chapel by the turn off at Tiroran to see ‘Macculloch’s Tree’. John Macculloch discovered it in 1819 when he was collecting information for the first geological map of Scotland that was eventually published a year after his death, in 1836. However, it was Chrissie MacGillivray, a lady then in her eighties, who I met two years later, in 1973 and who was the custodian of the tree for The National Trust for Scotland, that interested me the most. From the start, Chrissie, already ‘a legend in her own lifetime’, impressed me. The book I eventually wrote about her, which is a social history of Burg and Ardmeanach spanning two centuries, begins and ends with the fossil tree. It was to have been called ‘Chrissie and the Tree’, but its eventual title – Tea with Chrissie – was most apt because thousands of visitors were invited to tea with her. If you visited Mull before her death in 1989 then maybe you were too. Visitors to Mull would always be asked, “Have you seen Chrissie and the tree?”If not, they would be encouraged to do so, despite a long walk. Burg was the home that Chrissie had shared with her parents and seven siblings, and finally just her brother Duncan. It was the MacGillivray’s ancestral home that, in 1936, became a virtually un-endowed property of The National Trust for Scotland. Although the NTS inherited a ‘pig in a poke’, they were very excited when they discovered they also had an enormous fossil, uniquely preserved, within Mull’s basalt Staffa Suite. With the average chances of fossilisation in sediment being one in a million, preservation within an igneous rock is rare in the extreme.