A pedological study of soil genesis on Skidaway Island
Vanags, Christopher Paul
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Skidaway, a Pleistocene-aged barrier island, was chosen to study the transition between a Talquin fine sand (Arenic Alaquod) and an Ocilla loamy sand (Umbric Paleaquult) in a 15- by 40-m area. The objective was to characterize a young, heterogeneous landscape, which contained a soil association commonly found in older deposits inland. A detailed topographic map was generated, and the subsurface mapped with ground penetrating radar (GPR). GPR profiles were compiled to produce vertical slices, which were used to map the soil boundary. Exchangeable and soluble cations were measured for six profiles. Electrical conductivity, pH, gravimetric moisture, and particle size distribution were determined at 5 m increments over the grid. A 10% clay increase dramatically attenuated the GPR signal, producing slice images that resolve the boundary within 20 cm. An extensive microdepression corresponded with a change in parent material across the grid and at depth. Geochemical analysis showed order-or-magnitude shifts in pH and cation exchange capacity reflected by changes in vegetation at the boundary.