Some experimental data on slopewash and wind action with reference to quaternary morphogenesis in Belgium

This paper discusses field observations, field measurements, field and laboratory experiments concerning the physical weathering and the erodibility of sandy Tertiary rocks and loess mantles in Belgium. The observed phenomena and the experimental data have been discussed in terms of soil mechanics. Special attention has been paid to crack sets and desquamation in consolidated Tertiary sands resulting from lateral offloading, to the relative high erodibility of glauconiferous sands, and to the sensitivity of loess and loamy soils for solifluction, rainwash and colluviation. A stability index E has been proposed for loamy soils based upon the characteristics of the liquid limit curve. Two‐year observations and measurements at the dune station of Kalmthout have shown how the loess fraction can be transported in a basal drift near the ground, and how rainstorms provoke deflation and rainwash on dunes where gravel is moving in saltation during heavy storms. Litter flow has been found to occur on all actual forested slopes. All these data on morphogenetic processes have led to some considerations of the Quaternary morphological evolution of Lower and Middle Belgium: the modelling mainly by sheetwash of periglacial glacis, the evolution of the Hageland hills and of the Plateau of Brabant, the morphodynamics of loamy slopes, Late Glacial and Holocene dune building, and finally the Holocene evolution of forested slopes.