Genesis of Soils on Two Stream Terrace Levels on the Tennessee River

Abstract

Soils on two stream terrace levels along the Tennessee River, south of Knoxville, TN, were studied to evaluate genesis of stream terrace soils representative of the Southern Appalachian Ridge and Valley major land resource area. The soils on the lower terrace were described and sampled to a depth of about 12 ft, and on the upper one to about 17 ft. Iron oxides, Mn oxides and particle size variation with depth indicate that these soils formed during several periods of deposition. The older (upper) terrace soil had a well‐developed argillic horizon, moderate structure, up to 50% clay and appreciable free Fe oxide content. The soil on the lower terrace did not have well‐developed morphology, indicating it to be considerably younger than the upper terrace soil. Physical and chemical properties of the paleosol horizons showed that varying periods of weathering and soil development occurred following each episode of deposition. Clay illuviation and accumulation of Fe were good indicators of soil development in the paleosols. Sand distribution was a useful indicator of the depositional stratigraphy.