Investigation on the extent and effects of sub-aerial erosion on the chalk cliffs at Peacehaven
by Laura Dunton
Abstract This project looks at the effects of sub-aerial weathering on the chalk cliffs at Peacehaven taking into account both field and laboratory results. The accumulation of chalk debris on the promenade under the cliff provided information on the frequency and size of erosion events, showing little seasonal change from summer to winter. Weather data was correlated with this and provided a significant relationship between average rainfall and total debris. This has been interpreted as result of wetting and drying causing stresses and weaknesses to develop. Laboratory experiments to simulate frost shattering and salt crystallisation processes on chalk showed the influence of temperature fluctuations and salt solutions of varying concentrations. Samples saturated with environmentally realistic solutions exhibited greater breakdown during the salt crystallisation weathering process, reflecting the influence of wetting and drying on disintegration. It was also noted that high concentrations of salt solutions during freeze-thaw experiments caused increased breakdown. Cliff stabilisation works carried out at one of the field sites showed that weakening of the rock had occurred, this caused a short term increase in erosion. Such man made accelerations of erosion hold implications for residence and the council.
This project provided an over view of the weathering processes occurring at chalk cliff coastlines, however it also highlights the difficulty of attributing a weathering process to an erosional event.