The Dickson and Zanesville Soils of Washington County, Arkansas: I. Their Properties and Genesis

Abstract

AbstractThe Dickson and Zanesville soils of Washington County, Arkansas, exhibit very similar morphology although underlain by different bedrock. Purposes of this study were to determine certain chemical, mineralogical, and physical properties in order to establish their general composition and whether all or part of their sola were developed in loess. Data on three profiles of each series are similar. Some property ranges of their B22t horizons are: pH, 4.2 to 4.9; CEC, 12 to 16 meq/100g; base saturation, 14 to 27%; and clay content, 24 to 36%. Variations within series are of the same order as between series except the Zanesville has about 10% more fine or very fine sand and is usually somewhat lower in bases. A loess parent material is suggested by high silt contents (50% to 80%) and a lack of abundant coarse fragments in upper horizons. Conversely, uniform heavy mineral distributions and very fine‐to‐fine sand ratios with depth in both soils suggest that a definite upper loess layer does not exist and that Zanesville soils are mainly developed from underlying sandy siltstones and the Dickson soils from cherty limestone. It is postulated that porous cherts of the Boone formation can weather to silt as do siltstones. Since both are siliceous, similar soils could result.