Chalk coast dynamics: Implications for understanding rock coast evolution

Rock cliffs and shore platforms are linked components of the world's coastal zone. Understanding of the dynamics of their relationships has been hindered by the often imperceptible changes that occur within human time scales. The Cretaceous Chalk coasts of northwest Europe, and particularly those of southeast England, are among the most dynamic, and most intensively studied, cliffed rock coasts in the world. Perceptible changes to both cliffs and platforms have been measured on monthly, seasonal, annual and decadal time scales. Through a review of previously published data and the addition of data not previously published, average cliff retreat rates are calculated as 0.49 ± 0.38 m y− 1 and platform erosion rates 3.999 ± 3.208 mm y− 1. This paper highlights some of the interactions over time and space between process and measurement that continue to limit our understanding of the dynamics of rock coasts; in particular the link between rates of cliff retreat and platform erosion. It concludes by identifying fruitful areas for future research.

► We compile published and unpublished data on Chalk cliff and platform erosion. ► Rates vary significantly with measurement methods and spatial and temporal scales. ► Average erosion rates are 0.49 m y− 1 for cliffs and 3.999 mm y− 1 for platforms. ► The data highlight problems of linking and modelling cliff and platform evolution. ► There is a need for long term high resolution monitoring using a standard methodology.