Bearraich
Geological Conservation Review site | GCR #17 | Igneous Petrology | Tertiary Igneous
Scotland's geosites are chosen because of their local, national or international importance. Take only photos, leave only footprints: avoid causing any damage to this site. You can walk almost anywhere in Scotland without the need to ask permission or keep to paths, but you have a responsibility to care for your own safety, to respect people's privacy and peace of mind and to cause no damage.
This site is a Site of Special Scientific Interest (SSSI). It is an offence to intentionally or recklessly damage the protected natural features of a SSSI, and this includes unauthorised sample collection.
The right of access does not extend to quarries, building sites or any land where public access is prohibited, or to the collection of geological samples.
Summary
The south-western part of the Ardmeanach peninsula shows a representative and relatively well-exposed, continuous section through the lower part of the Plateau Lava Group of Mull and Morvern where the rocks are unaffected by pneumatolysis. The earliest flows - the Staffa suite - are characteristically columnar olivine-poor tholeiites which were erupted subaerially, as indicated by their reddened scoriaceous tops, but in places flowed into bodies of standing water. Features demonstrated to advantage include lava tubes, flow units, scoria and laterites. Associated with these lavas are well-known, large tree-fossils, the most famous being Macculloch's Tree. Above the Staffa suite lies the Main suite, mainly mildly alkalic to transitional alkaline-tholeiitic olivine basalts with a few feldsparphyric flows. Between 25 and 30 flow terraces can be identified from the base of the suite to the summit of Bearraich (432m).
Site information
Further information
https://www.cambridge.org/core/services/aop-cambridge-core/…
David W. JOLLEY, John MILLETT, Malcolm HOLE and Jessica PUGSLEY, 2024. Integrated photogrammetry, lava geochemistry and palynological re-evaluation of the early evolution of the topographically constrained Mull Lava Field, Scotland. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, volume 114, pages 193–217, 2023 (for 2024).
https://pubs.geoscienceworld.org/gsl/sjg/article/48/1/1/351…
Williamson, I.T. & Bell, B.R. 2012. The Staffa Lava Formation: graben-related volcanism, associated sedimentation and landscape character during the early development of the Palaeogene Mull Lava Field, NW Scotland. Scottish Journal of Geology, vol. 48, pages 1–46.
https://eprints.gla.ac.uk/148480/
Bell, B.R. & Williamson, I.T. 2017. Fossil trees, tree moulds and tree casts in the Palaeocene Mull Lava Field, NW Scotland: context, formation and implications for lava emplacement. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, vol. 107, pages 53–71.
Related geosites
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Location map from Jolley et al. 2024.
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Figure 6 from Jolley et al. 2024, showing details of MacCulloch's Tree site.
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Sept. 19, 2024
MacCulloch's Tree, showing fanning of cooling joints around cast of tree. Most of the original tree has been removed by collectors. Note that there is no fossil soil or tree roots beneath the tree, hence it was probably transported within a moving lava flow, then upturned.
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Sept. 19, 2024
Close-up of tree, showing markings of fossil bark.
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Sept. 19, 2024
Edge of tree with cooling joints, and ash bed with lava bombs to left.
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Sept. 19, 2024
'Daisy wheel' - horizontal cooling joints, possibly around a once-vertical tree, now gone; seen from path above cliff on way to MacCulloch's Tree.
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Sept. 19, 2024
Lava bombs and lapilli in ash bed below first lava.
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Sept. 19, 2024
Layer of ash and flattened and weathered lava bombs and splatter beneath first lava just to west of MacCulloch's tree. MacCulloch's Tree Flow of Staffa Lava Formation, earliest of Mull lavas.
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Sept. 19, 2024
Caves and other possible tree sites slightly north and west of MacCulloch's tree, showing fanning of cooling joints.
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Sept. 19, 2024
Rubbly base of lava above ash bed and below tree; note compaction at junction.
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April 25, 2015
View to Ardmeanach peninsula with lava plateau feature, from Ardtun.