Problems of Highland geology, past and present (lecture)

Dr John Mendum, BGS Edinburgh

The application of tectonic concepts developed both in Scotland and different parts of the world has strongly influenced the interpretation of the geological structure of the Scottish Highlands for at least 170 years. Escher von der Linth first mapped thrusts and “overfolds” in 1841. Lapworth recognised cataclasis and mylonitisation along thrust planes in 1882-3, and Bertrand introduced “nappes de charriage” in 1884. Bailey, in a series of papers between 1910 and 1940, took alpine terminology and ideas as the basis for his tectonic interpretation of the Grampian Highlands. This talk will look at the nature and origins of the major fold and thrust nappes that have been defined in the Highlands, ranging from the Moine Thrust Belt to the Highland Border, focusing at how such structures were recognised and defined. It will discuss what mechanisms of generation and emplacement have been proposed, their consequences, and what problems still remain in their interpretation.