The sand dunes lie at right angles to the prevailing wind and form a series of ridges, running roughly north-south, with lower lying areas between their crests. The long, linear depressions formed when a length of beach has been enclosed by newly formed dunes are known as "swales", whilst the smaller hollows are called "slacks".
The slacks and swales are sheltered from the wind and salt spray. They are often quite damp and may support temporary or even permanent ponds, because at certain times of the year the water table is not far below the surface. Also, plant and animal remains tend to accumulate in the slacks, which aids water retention. This means that species which cannot tolerate the harsher conditions on the crests of the dunes can become established.
Further inland, the slacks contain species that are common to damp pasture land, including many grasses, vetches, Hairy Hawkbit and Stinking Iris. The pale fleshy flowers of the parasitic Broomrape may be seen in the summer. Many of the plants found here provide food for the larvae of moths. Burnet Moths may be seen on Bird's-foot trefoil and their caterpillars construct their cocoons high up on grass stems where it is difficult for predators to reach them. The orange and black ringed caterpillar of the Cinnabar Moth feed on ragwort.
The insect and plant life of the slacks attracts many different birds, such as Skylarks, Yellowhammers and Magpies. Larks nest amongst the grass but are more likely to heard than seen. Many birds such as Linnets, Bramblings and Chaffinches appear in the area during the autumn and winter but nest further north during the summer. The Short-Eared owl preys on the many small mammals found in the dunes.