LIDAR-DERIVED DIGITAL ELEVATION MAPS OF THE DelMarva PENINSULA AND SOUTHERN NEW JERSEY USED TO IDENTIFY CAROLINA BAY LANDFORMS; THEIR PLANFORM SHAPE AND ORIENTATION CHANGES SYSTEMATICALLY WITH LATITUDE

The existence of Carolina bay landforms north of the Carolinas has been generally recognized for decades. Recent advances in digital elevation mapping using LiDAR (LIght Detection And Ranging) technology offer a new perspective on the location and shapes of these shallow basins and their enigmatic circumferal rims. To support a geospatial survey of Carolina bay landforms within Virginia’s Eastern Shore, Maryland, Delaware and New Jersey, we generated hsv-shaded DEMs (Digital Elevation Maps) as KML-JPEG tile sets for visualization. A majority of these DEMs were generated with LiDAR data, while a small subset used USGA 1/3 arc second data. A gentle progression of planform shape is seen on these maps as the viewer moves from south to north. We demonstrate that the planform of most bays identified suggests a very robust correlation to one of two archetypical shapes. These two shapes were engineered into Google Earth overlay elements, which were placed over candidate basins; by manually adjusting the length, width and rotation from North, the shape of the circumferal bay rim can often be satisfactorily captured. The generic Carolina bay characteristics set includes a pervasive common orientation among neighboring bays. However, as we traverse the coastal plain towards the north, the bays’ more-rounded presentation leaves this as a subjective assignment. Using LiDAR-derived imagery, we present our argument for the alignment suggestion that we imbedded in our archetype planform overlays. We demonstrate that when these archetype planforms are overlaid on the basins, their orientation varies systematically by latitude, in a gentle progression similar to that seen further south. The high fidelity LiDAR elevation maps also demonstrates the pervasiveness of the bay planforms against a backdrop of wind-driven sand sheets and parabolic dune formations across this landscape. All LiDAR maps referenced have been made available on the Internet to support independent research. Likewise, the geospatial database of metrics for 2,500 bays we examined in this region is available from an on-line Google Fusion Table: http://www.google.com/fusiontables/DataSource?snapid=S226571PxmB