Given these changes, there are several times when sea-level might be above the current height. Firstly, the earth at the peak of an interglacial is warmer than it is today. Britain, for example, had a tropical climate at the peak of the last interglacial: Hippo and Elephant skeltons have been found in London and Leeds (Story). This means that sea-level would have been higher, as there'd be less ice around. People have suggested a series of rock platforms around the British coast at up to 15m above sea level may be the interglacial high-water mark*. Equally, during glaciations, if the depression of the crust carries the land below the dropped sea-level it is possible there may raised beaches formed.

In the case of both last-interglacial and glacial beaches it is likely that any glaciers local to the beaches would have carried off any beach material. Raised beaches in glaciated areas (such as North Wales) that have material on them are therefore likely to be post-glacial - and in the north of Britain it is likely that these have been formed by the land re-bounding after glacial depression.

As the land rises back to its original position, any beaches forming will be left progressively further from the water. This is especially nicely seen at Jura, where the re-bound of the land can be seen in sequentially higher and higher (older and older) beaches.