TOPOGRAPHICAL EVOLUTION AS THE FOUNDATION FOR GEOMORPHOLOGICAL MAPPING IN THE COASTAL PARKS

The Inventory and Monitoring Program in the US National Park service is preparing geological maps for 270 National Parks and Historical Areas. Coastal parks present a particular challenge because traditional geological mapping of the subaerial surface is frequently limited to Holocene sand. Therefore, the scope of the coastal mapping effort has been expanded and is directed toward the character of the surface, the topographical features, or the production of geomorphological maps. The scholarly tradition of geomorphological mapping is based on the tenets of: 1. Metrics; 2. Formational processes; and 3. Sequential formation. That trio of attributes forms the basis for describing and mapping the feature classes in seven park units as undertaken by this team.

Aerial photographs and filtered LiDAR data sets are the primary sources of topographical information that are interpreted to generate the classes of geomorphological evolution in these parks. Some of the coastal parks have landscape elements created during the Late Quaternary augmented by more recent conditions. However, most are products of sediment accumulations during the Late Holocene sea level position. Although coastal parks are largely composed of a combination of active and stabilized dune systems, there is an opportunity to generate dune classes based on metrics, dimension and duration of the processes, and stages in the coastal evolution. That assemblage is the foundation of the geomorphological legend for these maps. Although largely focused on the natural processes, human interaction and modification of the surface features are additional elements in the classification of the coastal geomorphological elements.

Examples of the coastal geomorphological mapping products are presented for Sagamore Hill National Historical Site, including glacial, fluvial, and coastal morphologies: Fire Island National Seashore, incorporating ancestral, abandoned, and active dunal systems; and Gateway National Recreation Area, incorporating sequential active and abandoned dunal systems.