Soil chronosequence of the little river valley, atlantic coastal plain, North Carolina
Suther, Bradley E.
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A soil chronosequence of alluvial terraces along Little River in the Coastal Plain of North Carolina is characterized using soil morphology, chemistry, and mineralogy. Terrace ages are provided by optically stimulated luminescence (OSL) dating. The Little River valley contains a modern floodplain and five terraces that range from 9.3 ± 2.0 to 87.6 ± 17.9 ka. Morphological properties strongly correlated with age include solum and Bt horizon thickness, maximum percent clay, and rubification. Chemical properties strongly correlated with age include K2O concentration, dithionite-extractable iron, and the ratios of bases:alumina and bases:resistant oxides. Over time, a mixed clay fraction mineralogy is replaced by an assemblage dominated by kaolinite and gibbsite. Results indicate these properties are useful as age indicators over a timescale of 100 ka in this region. Comparisons with previous studies suggest there is considerable variability in age-related soil genesis trends among alluvial soils of the Atlantic Coastal Plain.