The formation and evolution of colluvium on arable land in northern Luxembourg

Abstract

The paper deals with colluvial deposits found in dry valley heads in a farmland area near the village of Berlé in northern Luxembourg. The colluvium, with a maximum depth of 1.50 m, overlies a truncated red and gray mottled IIBtb horizon of an older soil. The colluvium shows signs of groundmass illuviation in the form of matriargillans, matrans or agricutans, as this feature is variously called. These coarse grained cutans are also found in the buried IIBtb horizon, where they are superimposed upon illuviation ferriargillans. From a review of the literature it appears that matrans are generally considered to result from structural breakdown of the superficial soil horizons under human cultivation. That the colluvium was formed under cultivation is in agreement with its pollen content of practically only non-tree species associated with human occupation and cereals. The colluvium contains heavy minerals from a volcanic eruption in the Eifel which took place during the Upper-Pleniglacial or Late-Glacial of the Weichselian. Furthermore it is rich in charcoal fragments, presumably from charcoal burning after 1450 A.D. and/or from forest burning for agricultural purposes. The presence of pollen of Fagopyrum (buckwheat), which was introduced in the area around 1460 A.D., in the colluvium confirms a late-mediaeval and/or later time of formation of the colluvium.