Colluvium: Definition, differentiation, and possible suitability for reconstructing Holocene climate data

This study examines whether colluvial soils store climatic data and if these data can be used as proxies. Colluvial soils, as the correlated sediments of soil erosion, represent a widespread geoarchive. These soils store the morphology data of the eroded soils and contain clues as to the processes of the eroded soils' formation as well as indications of the pedogenesis which took place after the deposition. All of these processes are closely related to climatic factors, especially rainfall. This study discusses the genesis of young soils in colluvial sediments and shows that typical soil features may be related to climatic factors. Furthermore, the study investigates the genesis of anthropogenic colluvial sediments, which must be seen as a syngenetical product of relief, field size, time of usage, pressure of population, farming technique, sediment erodibility, deposition area, and climatic factors. To this end, pedogenic features are separated from the sedimentological features. The results show that the reconstruction of all factors which control the genesis of the formation of a colluvium is still not yet possible. This is the necessary precondition for colluvial soils to yield proxy climate data, or for the data to be correlated with already existing Holocene climate archives. As the results of our discussion are ambiguous in their interpretation, we conclude that colluvial soils, which clearly include climatic information, cannot be used for the reconstruction of proxy climate data at present.