Control Domains and Morphological Phases in Gravel Dominated Coastal Barriers of Nova Scotia

Abstract

Gravel dominated barriers are a major coastal feature of mid and upper latitudes indicating the active sorting of heterogeneous glacigenic sediments by wave action. Research over the last decade has suggested a sequential process for the development of gravel-dominated barrier coasts along the Atlantic coast of Nova Scotia, Controls on the development of gravel-dominated barriers are sediment supply, sea-level change, terrestrial basement geometry and wave climate. The variable interaction of these controls is shown to define distinctive process domains in which phases of barrier morphology develop. Sediment supply in its control on barrier alignment and barrier breakdown, is suggested as the most important of these variables for between-variation in the Nova Scotia barriers. Long-term (10a³) sea-level change controls the tempo of the transgression and thereby regulate macro-longshore sediment supply, Short term (<10a) sea-level rise may be influential in the rate of barrier breakdown. Barriers can be assigned by morphological structure to one of four main types of domains; growth, consolidation, breakdown and reformation. Some domains show different phases; growth has an inception phase and growth phase; breakdown has slow rollover, fast rollover and dissolution phases, Barriers may exhibit elements of several phases at the same time. Whether the phases are regarded as evolutionary is debated. The idea of phases being considered as the result of indeterminate activity is presented.