Soils of Steeply Sloping Landscapes in the Southern Appalachian Mountains

TLDR

The study area includes highly siliceous sandstone and siltstone in southwestern Virginia and granitic biotite gneiss in southwestern North Carolina. The study aimed to assess how slope aspect and position influence the transformation of parent rock into soil profiles at two southern Appalachian sites. Soils from north- and south-facing slopes were described, sampled, and analyzed to evaluate aspect and position effects. Soils derived from siliceous parent material were similar regardless of aspect and position, whereas soils from granitic parent material showed pronounced differentiation between slope positions and aspects, with north-facing soils dominated by kaolin and intergrade minerals and south-facing soils dominated by gibbsite.

Abstract

Abstract At two locations in the southern Appalachian Mountains, soils at two slope positions on north‐ and south‐facing landscapes were described, sampled, and analyzed to determine the relative effect of slope aspect and position upon the differentiation of the parent rock into soil profiles. At the southwestern Virginia study area, the parent rocks are highly siliceous sandstone and siltstone, whereas, the parent rock in southwestern North Carolina is a granitic biotite gneiss. Soils developed from the siliceous parent material were very similar in morphological, physical, chemical, and mineralogical properties irrespective of aspect and slope position. In contrast, there was a high degree of soil profile differentiation at the two slope positions and on the two aspects in North Carolina. In addition to differences in morphological and physical properties, there are distinct differences in the clay mineral suites on opposing aspects. Kaolin and the pedogenic 2:1–2:2 intergrade minerals are predominant in the soils of the north‐facing landscapes, whereas, gibbsite is the major clay mineral in the soils of the south‐facing landscape.