A LATEGLACIAL AGE FOR THE MAIN ROCK PLATFORM, WESTERN SCOTLAND

The sea-level record preserved in ancient shorelines forms a basis for studies of tectonic uplift, glacial loading, and the changing volume of the oceans. The existing record is derived largely from depositiona l features such as beach ridges and coral reefs, which contain materia l suitable for radiometric dating. Erosional shorelines have proved mo re difficult to date. Direct age estimates for shore platforms can now be obtained with exposure-dating techniques based on cosmic-ray-produ ced isotopes. Here we report measurements of cosmogenic Cl-36 on the M ain Rock Platform in western Scotland that indicate its formation in a postglacial event spanning less than a few thousand years. Together w ith isostatic modeling, the Cl-36 results suggest cutting during the Y ounger Dryas (in Britain, the ''Lateglacial'' or ''Loch Lomond'') Stad ial, when stable sea Level and severe climatic conditions combined to enhance bedrock erosion.