Late glacial environmental history and early soil formation in Northwest Switzerland

In 1996, well preserved deer bones, antler fragments and black grouse bones were found in a filled karst crack. Those animal remains were discovered in a limestone quarry in the Jura Mountains near Dittingen (canton Basel-Landschaft, Northwest Switzerland). The site is located in a gully of a dry valley beneath a loess covered high plain. In the framework of an archaeological excavation, the karst crack filling and overlying sediments (hill-washed loess, soils and colluviums) were documented. Samples for granulometry, geochemistry, micromorphology and palynology were analysed. The animal remains derived from the karstic fissure were radiocarbon dated to the early Bølling Interstadial (14’800 to 14’200 cal. BP). In addition, the palynological study shows that the overlying gully sediments were deposited between the Younger Dryas and the Middle Ages. The interdisciplinary investigation of the sediments revealed new insights into early soil formation processes, morphogenetic events and the vegetation history of periglacial environments. The new results clearly show that soil formation started immediately in the early Late Glacial. Decalcification and clay illuviation quickly developed in the course of intense vertical water flow through the sediment. It is therefore evident that luvisol development took place during the Late Glacial Interstadial (Bølling-Allerød Interstadial).