CONTROL DOMAINS AND MORPHOLOGICAL PHASES IN GRAVEL-DOMINATED COASTAL BARRIERS OF NOVA-SCOTIA

Gravel dominated barriers are a major coastal feature of mid and upper latitudes indicating the active sorting of heterogeneous glacigenic s ediments by wave action. Research over the last decade has suggested a sequential process for the development of gravel-dominated barrier co asts along the Atlantic coast of Nova Scotia. Controls on the developm ent of gravel-dominated barriers are sediment supply, sea-level change , terrestrial basement geometry and wave climate. The variable interac tion 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 th e most important of these variables for between-variation in the Nova Scotia barriers. Long-term (10a(3)) sea-level change controls the temp o of the transgression and thereby regulate macro-longshore sediment s upply. Shortterm (<10a) sea-level rise may be influential in the rate of barrier breakdown. Barriers can be assigned by morphological struct ure to one of four main types of domains; growth, consolidation, break down and reformation. Some domains show different phases; growth has a n inception phase and growth phase; breakdown has slow rollover, fast rollover and dissolution phases. Barriers may exhibit elements of seve ral phases at the same time. Whether the phases are regarded as evolut ionary is debated. The idea of phases being considered as the result o f indeterminate activity is presented.