Krotovinas — soil archives of steppe landscape history

Krotovinas, the burrows of small mammals, are common phenomena in steppe landscapes, and for a long time they have been a major point of discussions about the genesis of Holocene Chernozems. In addition, krotovinas provide a very valuable archive of the biological activities of soil, which is essential when stratigraphical ambiguities are to be solved. Despite this, krotovinas have received little attention within pedostratigraphical research. Using the example of the Upper Palaeolithic excavations Kostiënki and Borshchevo in the Middle Russian Steppe an integrative soil scientific approach highlights the importance of burrowing small mammals and of krotovina fillings resulting from both bioturbation and soil erosion in the Late Pleistocene. Based on field and laboratory data of sediments inside and outside krotovinas and 14C dating results from two sections, this systematic approach demonstrates the high value of the burrow fillings: black and humus-speckled fillings belong to deep burrows of hamsters dating to the period of Early Holocene Chernozem formation at the very beginning of the Preboreal (10–8 ka cal BC). Greyish sediments originate either from Ag–Bg horizons of the “Gmelin soil” (25–22 ka) or from other as yet unknown Late Valdai paleosols; these fillings are the result of the activities of shallow-burrowing lemmings. In addition, burrow fillings have provided optimal material for worms. Also, fossil bones and teeth found within krotovina fillings give new insights into the occurrence of Cricetus cricetus and Lagurus lagurus in this part of the Middle Russian steppe.

► A newly developed approach classifies burrow fillings in the Middle Russian steppe.
► Krotovinas are valuable archives if stratigraphical ambiguities are to be solved.
► Humus speckled krotovina fillings hold the Early Holocene Chernozem (10–8 ka BC).