Human and livestock faecal biomarkers at the prehistorical encampment site of Ullafelsen in the Fotsch Valley, Stubai Alps, Austria – potential and limitations

Abstract

Abstract. The Ullafelsen at 1869 m above sea level (a.s.l.) in the Tyrolean Stubai Alps next to Innsbruck is an important (geo)archeological reference site for the Mesolithic period. Buried fireplaces on the Ullafelsen plateau were dated at 10.9 to 9.5 ka cal BP and demonstrate together with thousands of flint stone artifacts the presence of hunter-gatherers during the Early Holocene. Grazing livestock has been a predominant anthropozoological impact in the Fotsch Valley presumably since the Bronze Age (4.2–2.8 ka). In order to study the human and/or livestock faeces input on the Ullafelsen, we carried out steroid analyses on 2 modern ruminant faeces samples from cattle and sheep, 37 soil samples from seven archeological soil profiles, and 9 soil samples from five non-archeological soil profiles from the Fotsch Valley used as reference sites. The dominance of 5β-stigmastanol and deoxycholic acid in modern cattle and sheep faeces can be used as markers for the input of ruminant faeces in soils. The OAh horizons, which have accumulated and developed since the Mesolithic, revealed high contents of steroids (sterols, stanols, stanones and bile acids); the eluvial light layer (E (LL)) horizon coinciding with the Mesolithic living floor is characterized by medium contents of steroids. By contrast, the subsoil horizons Bh, Bs and BvCv contain low contents of faecal biomarkers, indicating that leaching of steroids into the podsolic subsoils is not an important factor. High content of 5β-stigmastanol and deoxycholic acid in all soil samples gives evidence for faeces input of ruminants. The steroid patterns and ratios indicate a negligible input of human faeces on the Ullafelsen. In conclusion, our results reflect a strong faeces input by livestock, rather than by humans as found for other Anthrosols such as Amazonian dark earths. Further studies need to focus on the question of the exact timing of faeces deposition.