The Erosion Dynamics of the Peacehaven Shore Platform
by Philip Doyle
Abstract Peacehaven, East Sussex is home to an extensive shore platform at the base of its chalk cliffs and up to 200m of which can be exposed at low tide. This investigation is an insight to the erosion dynamics of this chalk shore platform. In 1977 work commenced on a major sea defence scheme covering the length of Peacehaven, the foundations of which are set into the shore platform.
Through the use of a Micro-Erosion Meter (MEM), Scanning Electron Microscope (SEM) and a Schmidt Hammer; micro erosion, rock porosity, and rock hardness were all measured to determine causes for varying erosion rates across the width of the shore platform.
Erosion results showed a 'bell' shaped distribution with higher rates at the sea wall base, mainly caused by increased localised abrasion; and at the seaward edge, primarily cause by increased porosity and softer rock. Porosity and rock hardness grew and reduced respectively the further away from the sample was taken from the sea wall.
Erosion results were also monitored around one of the groynes constructed in 1977. Through the use of the MEM and pinnacle measurements, erosion rates were found to be greater in runnel formations that their adjacent ridges, and on the eastern side of the groyne in comparison to the west. Average erosion rates around the groyne were calculated at 0.7mm per month. Pinnacle calculations stood at a comparable 0.86mm per month, calculated from 25 years of denudation.
Errors of the investigation methods and techniques are discussed, and a possible use of the data in a future management plan for the Peacehaven sea defences is explored.