THE VALUE OF ‘STAGE’ IN COASTAL GEOMORPHOLOGICAL MAPS (Invited Presentation)
Nearly all of the dunal features on the barrier islands originated as foredunes in active sediment exchange with an adjacent beach. Thus, the most basic separation distinguishes dune features that are actively developing versus those that are currently occupying some position other than adjacent to an active beach, creating categories of active foredunes and abandoned foredunes. Further segregations in sequence are made within the abandoned category, distinguishing between abandoned ridges associated with the modern shoreline and those associated with ancestral barrier positions. The “modern” abandoned ridges are former foredunes that are related to the active foredunes and they constitute a distinct stage in the barrier island evolution, albeit more recent than the ancestral forms. The “ancestral” foredunes are associated with a different island configuration and they constitute yet another stage, spatially and topographically distinct from the active dune/beach system and the “modern” abandoned foredunes.
Recent geomorphological maps for Fire Island National Seashore, Gateway National Recreation Area, and Assateague Island National Seashore exemplify ‘stage’ in coastal dune development as a central element in assessing the evolution of barrier systems.