Origin of Silt-Enriched Alpine Surface Mantles in Indian Basin, Wyoming
1990
Munn, L. C. | Spackman, L. K.
Three soil profiles developed over different bedrock (intrusive mafic pods and granite gneiss) in the Wind River Range, Wyoming were examined to determine the origin of their high-silt-content surface horizons. Particle-size distributions and clay mineralogy support the hypothesis that the soils have formed in surficial deposits derived from local bedrock materials. The soils are the product of physical (gelifraction) and chemical weathering, influenced by colluvial and (local) eolian transport processes. Mineral weathering has produced vermiculite and illite with an alteration or loss of chlorite and interstratified smectite-kaolinite. The silt-enriched mantles are distinctly different from loess. Frost action has resulted in silt and clay production in surface horizons and in mixing of materials throughout the profiles. Contribution from the Wyoming Agric. Exp. Stn. Journal Series no. JA 1612.
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