The ants milk the sugary secretions from the larval 'honey glands' and, in return, protect the larvae from predators and parasitoids, even going so far as to bury them at night. The caterpillar has green and yellow stripes to provide camouflage while it feeds on vetch. This provides a warm microclimate, suitable for larval development, which is also favoured by ants. The eggs are laid singly on very small foodplants growing in short turf. This species' sole larval food plant is the horseshoe vetch and it has a symbiotic relationship with red or black ants. Males have vibrant blue wings lined with a white margin, whereas the females are a rich chocolate brown. The rare Adonis blue can be seen in spring and again in autumn. The abundance of wildflowers provides homes for about thirty species of butterfly. Viper's-bugloss, a showy plant in vivid shades of blue and purple with red stamens, also grows along the cliffs.

It has yellow, white, or blue snapdragon-like flowers and about 90 per cent of the UK's population is found on the cliffs. The oxtongue broomrape is an unusual plant that lives on the roots of a host plant. Rock samphire is an edible, salt tolerant succulent plant that grows on the cliff's slopes. Cliff erosion and changeĪmong the wildflowers are several varieties of orchids, the rarest of which is the early spider orchid, which has yellow-green to brownish green petals and looks like the body of a large spider. A single hardground may have been exhumed 16 or more times before the sediments were compacted and hardened ( lithified) to form chalk. Hardgrounds are thought to reflect disruptions in the steady accumulation of sediment when sedimentation ceased and/or the loose surface sediments were stripped away by currents or slumping, exposing the older hardened chalk sediment. In some areas, layers of soft, grey chalk known as a hardground complex can be seen. Several different ocean floor species such as brachiopods, bivalves, crinoids, and sponges can be found in the chalk deposits, as can sharks' teeth. Quartz silica filled cavities left by dead marine creatures which are found as flint fossils, especially the internal moulds of Micraster echinoids. The cliffs' chalk face shows horizontal bands of dark-coloured flint which is composed of the remains of sea sponges and siliceous planktonic micro-organisms that hardened into the microscopic quartz crystals. At the end of the last glacial period, around 10,000 years ago, rising sea levels finally severed the last land connection. A land connection across the southern North Sea existed intermittently at later times when periods of glaciation resulted in lower sea levels. The land masses remained connected until between 450,000 and 180,000 years ago when at least two catastrophic glacial lake outburst floods breached the anticline and destroyed the ridge that connected Britain to Europe. Until the end of the last glacial period, the British Isles were part of continental Europe, linked by the unbroken Weald-Artois Anticline, a ridge that acted as a natural dam to hold back a large freshwater pro-glacial lake, now submerged under the North Sea. Due to the Alpine orogeny, a major mountain building event during the Cenozoic, the sea-floor deposits were raised above sea level.

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