Deglaciation of the eastern Cumbria glaciokarst, northwest England, as determined by cosmogenic nuclide (10Be) surface exposure dating, and the pattern and significance of subsequent environmental changes

A cosmogenic nuclide is formed when an atom of one element is struck by cosmic rays (which are a part of "sunlight") and changes into a different element. Beryllium-10 is one such nuclide. In the case of rocks exposed to sunlight, new nuclides are created //in situ and build up over time in the surface layer. By counting the number of these nuclides (and with a correction factor for surface weathering), it is possible to determine how long a rock surface has been exposed. In this study, four glacial erratic boulders were tested and their age of deposition calculated at 17,000 years ago. The boulders were of Shap granite and they had not travelled far from their source, so the local ice mass must have been wasting away at this time. Comparative studies show that the end of the last glacial period occurred slightly later in the Lake District (to the west) but slightly earlier in Lancashire and Yorkshire (to the south). The authors then give an informative summary of climate change in the local area since deglaciation