Saprolite, soils, and sediments in the Rhenish Massif as records of climate and landscape history

The Rhenish Massif, at the western boundary of Germany, consists predominantly of Devonian slates and siltstones, which over large areas have been altered to saprolite. The distribution and characteristics of saprolites, Pleistocene periglacial slope deposits (PPSD), Holocene colluvium and soils were investigated along a 2.5 m deep gas pipeline ditch in 20 sections with an overall length of 19 km.The results are used for landscape history reconstruction. Under warm-humid conditions of the Upper Mesozoic and Lower Tertiary, intensive weathering led to formation of a planation surface covered by thick saprolites and kaolinitic soils. During Pleistocene glaciations, the area experienced periglacial conditions that resulted in erosion of the soils and parts of the saprolites. Several layers of PPSD developed. During the Holocene no significant slope processes occurred, until human deforestation led to accelerated hillslope erosion. As a result, today the PPSD are partly eroded or covered by Holocene colluvium in many places. The sediment distribution follows distinct rules. Generally, the sediment thickness increases downslope. Concave slope sections show a substantial increase in thickness and number of preserved sediment layers. The soils developed in PPSD on saprolite are primarily Planosols, while Cambisols and Luvisols predominate in PPSD on fresh rock.