Laboratory abrasion tests on beach flint shingle
Laboratory tumbling experiments demonstrate that rounded flint beach shingle is less durable than commonly supposed. The mean rate of abrasion for dark grey Sussex flints (Senonian) in the first few hours of tumbling increases with weight whereas that of white Normandy flints (Turonian and Coniacian) does not. Depending on pebble weight, the Sussex flints abrade at up to six times the rate of the Normandy flints. Abrasion rates also vary according to tumbler load, the watenshingle ratio, and tumbling period. The abrasion rate of Sussex flints decreases with time at a much greater rate than could be expected from the reduction in size. The abrasion debris is mostly silt sized, but small quantities of sand are produced from samples containing larger pebbles. In situ abrasion of flint shingle is estimated to be significant, reducing the protection shingle beaches afford to cliffs thus exacerbating Chalk cliff instability.
Figures & Tables
Most of the rocky coastlines around the world are subject to active erosion processes. Because of the growing hazard to local communities from coastal cliff retreat, it is necessary to investigate where, when and how cliffs collapse. The results of these studies are vital for the planners and local authorities responsible for safety and access to cliffs and beaches. This volume focuses on the coastal chalk cliffs of the English Channel, where a multidisciplinary approach has been used to understand active coastal cliff recession.
The book is organized around three main themes: the geological factors controlling cliff instability, the marine parameters influencing coastal erosion and the use of some new tools for hazard assessments.
This volume will be of use to academics and professionals working on rocky shores, with an interest in sedimentary geology, stratigraphy, tectonics, geomorphology, engineering geology, coastal engineering and GIS.