Properties of Alpine Soils Associated with Well-Developed Sorted Polygons in the Uinta Mountains, Utah, U.S.A.

Abstract

ABSTRACT Twelve profiles of alpine soils associated with well-developed, but currently inactive, sorted polygons were investigated in the Uinta Mountains of northeastern Utah. The summit upland in the Uintas does not appear to have been glaciated, and these soils are considerably older than those located in lower elevation glacial valleys. Profiles of soils from the polygon centers reveal a dark, organic-rich surface horizon developed in loamy loess overlying a series of redder, sandy B horizons locally exhibiting strongly developed platey structure and pockets of coarser sediment. Irregular and broken horizons at depth reflect extensive cryoturbation during episodes when the sorted polygons are active. Overall morphology and profile quantities of weathering products in these soils are similar to those previously reported for alpine tundra soils in the Uintas; however, the cryoturbated horizons are limited to soils in the patterned ground. A developmental model for these soils emphasizes the combined role of pedogenic processes operating during interglaciations (accumulation of organic matter and loess, translocation of silt and clay, chemical weathering) and periods of cryoturbation (distortion of horizons, redistribution of weathering products within the solum). Outstanding questions include the timing and relative duration of cryoturbation episodes, the timing of loess deposition, and the overall age of the soils.