Krotovinas, pedogenic processes and stratigraphic ambiguities of the Upper Palaeolithic sites Kostenki and Borshchevo (Russia)

The excavations of the Upper Palaeolithic sites of Kostenki and Borshchevo, located in the Middle Russian Plain, bear several meters of loess-derived colluvial deposits of the Middle and Late Valdai, which cover alluvial sediments of the Don floodplain. At least four cultural layers and more than three paleosol units occur within the colluvial deposits. A high number of krotovinas is most obvious, mainly the burrows of Cricetus cricetus and Lagurus lagurus, which on first view seem only to disturb sediment and soil stratigraphy. To disprove this assumption, the present paper investigates the significance of krotovina fillings within soil research by applying micromorphological analysis. The study gives insight into different filling materials, soil forming processes inside abandoned and filled burrow systems, and surrounding material. In some cases, krotovina fillings in this part of the Middle Russian Plain can be areas of bulking and compaction, of preferential paths of infiltration followed by calcium carbonate depletion, and of drying followed by secondary calcification. Further, burrows are paths for second and third generations of soil faunal activities.