Chesil Beach, between Weymouth and Abbotsbury, is a huge bank of pebbles, which are graded. Various theories exist about how it originated. However, behind the pebble ridge there are a couple of lagoons, a sort of fossil beach – or is it? In February's issue of the BBC CountryFile magazine there is a short piece on unusual beaches in various parts of the country. For example, along the eastern North Sea shore there are several examples of sea spits and sandbars. In contrast, on the south coast there are what is known as barrier beaches, beaches that have formed behind a barrier. One such is Slapton Ley in Devon, famous for its connection with the Normandy Landings in WWII (where they trained etc). Another is the lagoons behind Chesil Beach, and it seems they formed when Holocene sea levels stopped rising – at around 3000BC. The sea level change is of course thought to be gradual, but if instead, they proceeded in jumps and starts and have a connection with changes at the axis of rotation, fairly small changes, and then the lagoons were formed on the very last occasion this happened (see also Paul Dunbavin's books available from the SIS Book Store).