THE IMPORTANCE OF AUTOGENIC PROCESSES IN THE DEVELOPMENT OF BEACH RIDGES IN AREAS UNDERGOING UPLIFT DUE TO POST-GLACIAL REBOUND

Beach ridges are common landforms found along coasts undergoing isostatic rebound or other forms of relative sea-level fall. The development of individual ridges has been attributed to storms, tidal cycles, and even the change in the rate of relative sea-level. However, few studies have investigated the role of autogenic processes in the development of individual ridges. In this study, we modify the existing code for modeling beach/foredune-ridge and swale morphology to examine the development of beach ridges during conditions of falling relative sea-level and constant sediment supply. We show that individual beach ridges can form in the absence of changes in the rate of sea-level change, tidal cycle, sediment supply, and storms. New beach ridges form as the shoreline moves seaward due to relative sea level fall, removing older beach ridges from their source of sediment, thus nucleating new beach ridges. Furthermore, we find that beach ridges grow higher and more frequent with increased rates of sediment supply. This study highlights the importance autogenic processes play in beach ridge development and has significant implications for the ability to decipher between environmental signals using beach ridges as historical archives.