Paper No. 2
Presentation Time: 8:30 AM
A PROPOSED TAXONOMY FOR CAROLINA BAY CIRCUMFERENTIAL RIM PLANFORMS; FINDINGS OF ROBUST ADHERENCE TO DISTINCTIVE ARCHETYPES IS SUPPORTED BY LIDAR-DERIVED DIGITAL ELEVATION MAPS
A 1930 aerial photographic survey of Horry County, South Carolina, revealed vast fields of aligned elliptical landforms, sparking intense scientific research into their geomorphology. Today, Digital Elevation Maps (DEMs) generated using the remote sensing technology of Light Detection And Ranging (LiDAR) accentuate the visual presentation of these shallow basins by elucidating their closed circumferential rims. While the planform of these “Carolina bays” is considered to be elliptical, we document the existence of subtle, yet distinctive, regional variations in the shape of their closed planforms. Six archetypes are offered as taxonomy: bay, bayBell, bayShore, bayOval, baySouth and bayWest. To support a geospatial survey of these enigmatic landforms, 500,000 km2 of hsv-hinted (hue-saturation-value) DEMs were generated using publically accessible LiDAR data. Here, I describe the DEM image generation process, and their integration as tile sets into Google Earth for visualization. My measurement protocol involves manually placing an appropriate archetype planform template - as a PNG image "overlay" - onto the Google Earth virtual globe, then sizing and rotating it so that a satisfactory representation of a particular bay’s rim is achieved. The resulting overlay data element is programmatically processed to generate bay characteristics such as geographic location, elevation, surface area, and major axis spatial orientation. Over 40,000 distinct Carolina bays have been measured using the methodology described. Although the visual pattern matching process is to some extent subjective, the robust adherence of thousands of bays to this set of planforms supports the taxonomy's relevance. The resulting data are publically accessible from Google’s Fusion geospatial data repository facility, both in tabular form and in situ on the virtual globe. Preliminary findings from the survey are discussed, such as how the distribution of the archetypes and the spatial orientation of the bay’s major axis vary systematically by latitude and longitude across North America. The availability of this extensive spatial data set may assist in identifying the geomorphology of these enigmatic landforms. The processes demonstrated here might be applicable to the geospatial analysis of other landforms on Earth and the planets.