Geological processes have forged an atypical region of geomorphic and stratigraphic diversity in the Ridge and Valley physiographic region of East Tennessee. Soils developing in the melange of parent materials reflect this heterogeneity. Objectives of this study were 1) to better understand the geological stratigraphy of the Ridge and Valley area, 2) to determine the genesis of soils forming in a variety of parent materials, 3) to examine soils forming in specific parent materials to discern properties uniquely characteristic to those soils, 4) to identify specific properties utilizable for field recognition of these soils, and 5) to classify these soils to the family level.
Within the Whiteoak Mountain fault block, geologies range from the Cambrian Rome Formation to the Ordovician Moccasin Formation. Properties of each rock unit vary to some extent. This complexity has induced a great diversity in soil genesis.
Sixty-one pedons from the Whiteoak Mountain thrust block were sampled for soil genesis and classification. A transect of thirteen soils was examined over a sequence of Cambrian to Ordovician aged geological units including the Rome Formation, Knox Group, and the Chickamauga Group. Soil genesis of forty-eight pedons directly related to the Copper Ridge Formation and the Maryville Formations were studied in Roane and Anderson Counties, Tennessee.
Soil morphology was described for each site. Horizonization, texture, structure, consistency, redoximorphic features, and any other observable property was noted during excavation. Laboratory analyses for soil characterization included pH, total carbon, particle size, free iron oxides, cation exchange capacity, percent base saturation, total acidity, KCl extractable aluminum, and hydroxylamine-HCl extractable manganese.
Parent materials in the thirteen soil transect included alluvium, colluvium, and residuum. Soils evolved from Chickamauga Group geologies were classified as Typic Paleudults and Typic Hapludalfs. Classification of soils developing in materials from members of the Knox Group IV included Typic Paleudults, Typic Fragiudults, Typic Kandiudults, Typic Hapludalfs and Typic Hapludults. The Rome Formation had weathered to form soils classified as Ultic Hapludalfs and Typic Hapludults. Soils derived from fault breccia and an alluvial/colluvial deposition were classified as a Typic Hapludalf and Typic Hapludult, respectively. The primary differences among these pedons resulted from the influences of geological parent material, site position, slope, and erosion.
Soil formation in Copper Ridge parent materials resulted in development of low activity clays with kandic horizonization. Of the 24 pedons examined, 54% had developed kandic horizons. Kandic horizons with hues of 5YR and 2.5YR had average clay contents of 49 and 68%, respectively. Non-kandic argillic horizons averaged 34 and 55% clay in the 5YR and 2.5YR horizons. Kandic horizons had developed in both colluvial and residual materials. For field identification, intense redness of soil matrix color along with high clay content in soils forming in Copper Ridge colluvium/residuum would present a greater than 54% possibility that kandic horizonization had occurred.
Soil evolution in Maryville parent materials was very consistent over the twenty-four pedons examined. These soils were not very deeply weathered. Paralithic contact occurred at less than 100 cm in 75% of the pedons. Particle size class was predominantly clayey. Classification varied primarily due to thickness of the argillic horizon. Forty-two percent were Ochreptlc Hapludults, while the remaining 58% were Typic Hapludults.
Weathering of the diversity of rock units in the Ridge and Valley physiographic region has resulted formation of a variety of soils. Soils properties were directly related to the geological parent material with variations primarily resulting from differences in site position. Knowledge of the geological lithologies of a region is a valuable tool in the examination of soil genesis and classification
