Long-Term Denudation and Geomorphology in Scotland

Long-term geomorphology has received little recent attention in Scotland. Palaeosurfaces and major landforms, including valleys and basins, can be linked to the sub-Caledonian and sub-Permian basement unconformities. The present topography was sculpted from the sub-Palaeocene unconformity after kilometre-scale uplift in response to Early Palaeogene magmatism. Recent results from thermochronology indicate an eastward decrease in denudation across Highland Scotland that is supported by landscape persistence in eastern areas since the Devonian. A sequence of planation surfaces developed from the Late Eocene onwards in intervals of slow uplift and high sea levels. The highest extensive surface, the Eastern Grampian Surface, has been uplifted to an elevation of 500–840 m. The surfaces formed by etch processes operating in response to changing base levels under warm-to-cool, humid environments, with extensive forests and widespread deep weathering. After uplift, each planation surface was modified through valley incision, backwearing of scarps and downwearing. Pliocene sea-level fall likely led to formation of coastal platforms that included precursors of the present Hebridean strandflat.