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Highland Boundary Fault

This is just one of many places where the Highland Boundary Fault is clearly visible, with level agricultural land suddenly giving way to mountains. A significant geological discontinuity, this Fault crosses Scotland from Arran to Stonehaven, separating the Highlands from the Midland Valley. To the north and west lie hard metamorphic rocks of the Dalradian group and to the south and east softer, sedimentary rocks (mainly Old Red Sandstone) of the Devonian and Carboniferous periods. The Fault runs southwest-northeast from Arran, across the Firth of Clyde, Loch Lomond, Aberfoyle, the Menteith Hills, Callander, Comrie and Crieff to where this photograph is taken. Farther north-east it forms the northern edge of Strathmore before reaching the North Sea beside Stonehaven.