Understanding colluvial deposits

Abstract

During the Holocene, humans have decisively shaped their environment by becoming ecosystem engineers. The advent of sedentism led to the expansion of agricultural areas, unintentionally causing widespread soil erosion, forming colluvial deposits. These often multi-layered colluvial deposits, which particularly occur along slopes and depressions, serve as crucial geoarchives of human-environment interactions. Using a simplified erosion–deposition model of the formation of multi-layered colluvial deposits without considering pre-burial postdepositional processes in each colluvial layer can lead to incorrect interpretations or, at best, to an underestimation of the high value of colluvium as geoarchive. Therefore, this study discusses different scenarios of possible pre-burial postdepositional changes in soil properties of individual colluvial layers, with and without human influence, and how these changes may affect the interpretation of dating results. After the deposition of a colluvial layer, influences such as ongoing agricultural activities can homogenise the respective layer, so that it is an analytical challenge to distinguish between originally successive erosion/deposition events and ultimately to establish a robust model age for the time of their deposition. By integrating high-resolution archaeopedological analyses, we explore how agricultural activities and pedogenic processes alter post-depositional soil properties, complicating the distinction between successive deposition events. The findings highlight the importance of considering non-linear correlations and post-depositional changes to establish accurate models of land-use history and erosion/deposition events.