At Birling Gap the geology is slightly different, and this can best be seen by looking back at the cliffs from the beach at low tide. It is a dry valley underlain with coombe rock. This valley was created during the last Ice Age (which lasted until about 12 000 years ago). The coombe rock is much softer than the chalk and so it erodes at a faster rate, causing a slight ‘bay’ at Birling Gap.
Most of the coastline in the south east of England is either built up or protected through sea defences. This has not happened at the Seven Sisters which has remained unspoilt thanks to the long history of National Trust and East Sussex County Council ownership. These cliffs and the wave cut platform below are important both nationally and internationally for their biology and geology. They provide spaces for specialised plants and animals to thrive, and also a safe habitat for nesting birds such as fulmars, kittiwakes and peregrine falcons.