The cliffs are formed of chalk laid down in the Cretaceous period between 65 and 100 million years when Britain lay closer to the equator and was covered by a warm shallow sea. Chalk is formed from microscopic plankton which dies and sinks to the seafloor, their shells being compressed into chalk. These layers were folded during the same earth movements which formed the Alps. The resulting chalk dome was eroded to leave the two chalk ridges of the North and South Downs, with softer clays and sandstones forming the low lying Weald. Soft brown sandy deposits washed out from glaciers were deposited on top of the chalk as the ice receded at the end of the last Ice Age. Erosion by the sea and rivers has resulted in the undulating landscape we see today.
Chalk is relatively soft and is subject to erosion from constant wave action by the sea. Average erosion is about 4cm a year but in periods of severe storms several metres can be lost over one winter. Please stay away from the edge, both at the top and the bottom of the cliffs, as cliff falls can occur at any time.
On a windy day you can find shelter from the prevailing south-westerly winds along the path to Hope Gap where steps lead down to the beach. The path along Hope Bottom passes through woodland and scrub opening out to give views of the sea. This area is an important stop off point for migrating birds in spring and autumn. The vegetation is controlled to keep the paths open and allow flowers to grow providing nectar and pollen for insects and the many bees and wasps, including the rare potter flower bee Anthophora retusa. These nest in the sandy deposits overlying the chalk at the top of the cliffs. On a warm day the cliff beside the steps leading down to the beach is alive with insects and many small nest entrance holes can be seen below the pink thrift tumbling over the cliff edge. On the slopes around Hope Gap, moon carrot, a rare relative of wild carrot, is seen during September.
The main track from the car park leads down past the coastguard cottages, some of which are still occupied. The small single storey building is the cable hut which was constructed in 1917 to house the first telephone cables to cross the English Channel to France. At the mouth of the Cuckmere a small saline lagoon contains some rare beetle species (including Berosus fulvus and Philorhizus vectensis) and an area of vegetated shingle has yellow horned-poppy, sea milkwort and rock sea-lavender.
On the beach a wave cut platform of more resistant chalk has been eroded into intricate patterns forming pools and channels. Interesting sea life can be found in these pools at low tide and rock pooling is popular with families. As there is no exit from the beach, do not walk east along the beach towards Seaford unless you have checked the tide times.
There are two main areas linked by a narrow coastal strip. In the east, adjacent to the mouth of the Cuckmere, and easily accessed from South Hill Barn car park, is an area of chalk grassland. We are improving this rare habitat by controlling the spread of scrub and rank grasses.
The western side of the reserve next to Seaford Head Golf Course is accessible by a footpath from Chyngton Way, or by walking from Seaford seafront up the substantial slope of Seaford Head. If approaching from this side you pass the site of an Iron Age hillfort where it is possible to cross the golf course (with care!) and explore the paths through the scrub, or to continue along the cliff path to Hope Gap. With the help of our invaluable local volunteer group we are improving this area by removing some of the vegetation to create more variety in age and structure which will lead to greater diversity in the flora and fauna. Part of the reserve lies within the boundary of the golf course where we work with the Greenkeeper to encourage a mowing regime more sympathetic to wildlife. The chalk grassland on this side has been neglected in the past so we have introduced sheep grazing and this is already starting to make a difference to the quality of the sward. In future we will see an increase in the number and variety of wildflower species. When sheep are grazing please keep dogs on a lead.