"The soft bits of the shoreline below me are distinctly mobile and dynamic, as geographers say. A map from 1838 shows dunes nudging out from the headlands at either end of a long, sandy beach, with tongues of bare sand licking far back into the land. By 1919, the dunes from one end had thrown a protective arm halfway across the beach, with a big lawn of wind-levelled machair and a couple of large lagoons forming up behind them."