THREE Scottish sites have been included in a new list of 100 geological sites of “international scientific relevance”.
The Parallel Roads of Glen Roy, near Spean Bridge in the Highlands, the Rum Igneous Complex, on the Isle of Rum, and the “Barrow Zones”, at the Highland boundary fault near Brechin, have all made the list.
Each of the areas were selected by the International Union of Geological Sciences (IUGS) for their geological heritage and global importance.
The full list of 100 sites, which was drawn up by more than 700 experts from 80 nations and 16 international organisations, was announced during the 37th International Geological Congress in Busan, South Korea on Tuesday.
The Parallel Roads of Glen Roy
The three Parallel Roads of Glen Roy, which are around 15 miles of Ben Nevis, are three ancient glacial lake shorelines which have left visible straight lines across the hills.
The lines were “some of the most mysterious features identified in the landscape during the 18th and 19th centuries, attracting much speculation at the time”, according to the British Geological Survey (BGS).
NatureScot geomorphologist Dr Christina Wood explained: “Glen Roy and neighbouring Glen Spean have stimulated geological debate from the early-nineteenth century to the present day.
“Particular highlights are three shorelines, or 'parallel roads', visible along the flanks of Glen Roy at altitudes of 260m, 325m and 350m above sea level. The lakes that created the shorelines were dammed by glaciers as they advanced and retreated.
“The parallel roads provided convincing evidence for the former existence of glaciers in an area where none exist today, thus supporting [Louis] Agassiz’s theory of continental glaciation during a geologically recent Ice Age.”
The Rum Igneous Complex
The Rum Igneous Complex, which is in the Rum National Nature Reserve, is regarded as “the internal plumbing of one of Scotland’s most recently active volcanoes in which chromium and the precious metal platinum accumulated in chambers of molten magma”, NatureScot said.
However, the volcanoes on Rum aren’t believed to have been active for the last 60 million years.
The remnants of activity represent an “exceptionally well exposed suite of ultrabasic, basic and gabbroic rocks and granitic intrusions”, according to a 2014 paper from the late petrologist CH Emeleus.
Barrow Zones
The Barrow Zones, just north of the Highland boundary fault near Brechin in Angus, were once mud on an ancient ocean floor, NatureScot said.
Changes in the mineral content of rocks, up Glen Esk, show that the area experienced increasingly higher pressures and temperatures, in a north-westerly direction, when plate tectonics brought the geological foundations of Scotland together around 470 million years ago.
The area is named after the geologist George Barrow, who studied the area and published papers on it from 1893 to 1912. Barrow wrote in his 1893 paper that the “area contains several masses of intrusive rock which are probably connected underground, and that the highly crystalline character of the surrounding schists is mainly the result of thermometamorphism”.
Along with 97 other sites across the world, the newly published 100 make up the second IUGS list of sites which are of the “highest scientific value”.
NatureScot said in a press release: “They are the world’s best demonstrations of geological features and processes. They are the sites of fabulous discoveries of the Earth and its history.”
The first list, which was published in 2022, included Siccar Point in the Scottish Borders as its very first entry. The site was where father of modern geology James Hutton saw geological formations that hinted at the age of the earth and its natural processes.
The Moine Thrust in the northwest Highlands was also recognised in the first list, and the third is due to be published in 2026.
NatureScot geomorphologist Dr Christina Wood said: “It’s fantastic to see three Scottish sites being recognised for their internationally important contributions to geological science.
“We’re particularly proud that both the Parallel Roads of Glen Roy and the Rum Igneous Complex are located on NatureScot’s National Nature Reserves.”
She added: “It’s vital we protect and conserve these special places for future generations to learn from and enjoy and we hope that many more people will continue to explore and experience the wonders of Scotland’s truly magnificent geological heritage.”
