Formation of Colluvisols in different soil regions and slope positions (Czechia): Stratification and upbuilding of colluvial profiles

•Peaks in colluviation dated to High and Late Middle Ages and last 70 years.•Pre-Neolithic colluviation identified at both study plots.•High energy deposition in toe-slopes, slow gradual sedimentation in side valleys.•Effective combination of luminescence dating and anthropogenic substances activity. Colluvisols represent a significant part of the erosional catena in undulating landscapes, often changed by long-term agricultural management. The present study provides a detailed description of the stratigraphy, properties and development of colluvial profiles in two geologically, climatically and historically different areas of Czechia, situated in the loess region of South Moravia and Central Bohemian Upland, built on plutonic rocks. For the first time in Czechia, colluvial profiles were dated and interpreted in terms of the history of human impact on the landscape and Holocene climatic fluctuations. Four profiles were excavated in the toe-slope and side valley areas. A multidisciplinary approach combining absolute dating by optically stimulated luminescence, assessing 137Cs activity and micromorphological, mineralogical and geochemical analysis was applied to identify the period and mode of deposition of each layer. In both areas, a predominantly rapid, event-based sedimentation with thick recently deposited layers was identified in the toe-slopes, while the side-valleys are characterized by gradual, slower and older sedimentation. Peaks of erosion activity at both plots were distinguished in the High and Late Middle Ages and the recent period since 1950. In both periods, significant changes in anthropogenic pressure on the landscape, whether due to increased population density or agricultural intensification, were identified as the main trigger. Nevertheless, significant associations were also found with climatic events in the periods in question. In both areas, colluvial layers corresponding to the pre-Neolithic period were also found, probably exclusively associated with the influence of contemporary climate.