Relict cryopedogenic features in soils with secondary carbonate horizons, Western Wyoming, USA

We document relict cryopedogenic features in strongly developed calcic horizons on a flight of fluvial terraces in a mid-latitude, intermontane basin in western Wyoming, USA. The calcic horizons show many distinctive cryopedogenic features including relict sand wedges, involutions, mixed horizons, fragmented and displaced carbonate/silica stone pendants and indurated soil material, and vertically oriented stones. Evidence of mixing, fracture, displacement and orientation of soil materials, independent of evidence for biologic or recrystallisation processes, strongly suggests cryoturbation. The soils also include micro-scale features such as orbiculic and suscitic fabrics, vesicular and elongated pores, shattered pedogenic ooids and sand grains, and platy to blocky microstructure. The micro-scale features are likely related to seasonal frost. The calcic horizons do not include progressive morphological differences across the upper eight terraces in the study area. The overall similarity is likely caused by the fracturing and mixing processes associated with cryoturbation. There is a need to further document cryoturbation features in calcic horizons to understand the specific cryogenic processes related to their genesis. Cryoturbation implies movement and mixing of soil material. Thus the recognition of relict cryoturbation features in mid-latitude calcic soils may have significant implications regarding their use for geochronology, palaeoenvironmental and palaeoclimatic reconstruction. Copyright (c) 2007 John Wiley & Sons, Ltd.