Soil dynamics along an escarpment of a quartz sandstone tableland

Long-term geomorphic evolution of tablelands involves various mechanisms and processes. The retreat of peripheral escarpments is assumed to be of key significance. How soils evolve on escarpments undergoing retreat and what they tell about the pace of this retreat is poorly understood. To address this knowledge gap, the following research questions were set: (a) How do the composition and the properties of soils change with distance from a sandstone caprock escarpment? (b) What is the weathering state of the soil material? (c) How do erosion and deposition rates compare within an escarpment cliff?

The Stołowe Mountains in Poland provide a spectacular tableland landscape where a sandstone caprock overlies mudstones and marls, resulting in morphologically bipartite slopes, with a cliff line at the top and planar to concave slopes below. Eight profiles along a toposequence within the escarpment of Urwisko Batorowskie were investigated. By using the fallout radionuclides ^239+240Pu as a tracer, soil erosion and deposition rates along the sequence were assessed. For a comprehensive understanding of soil characteristics in relation to erosion processes, weathering severity was characterised by using weathering indices. Soil dynamics were further investigated using a portable optically stimulated luminescence reader. The soils exhibited complex characteristics and varied from Podzols to Stagnosols, Gleysols and possibly polygenetic soils. Soil erosion and deposition rates showed a high variability along the slope, with erosion rates of 0.5–6.4 t ha⁻¹ yr⁻¹ and deposition rates of 0.2–6.9 t ha⁻¹ yr⁻¹, and thus an almost equal mass balance. Weathering indices and luminescence measurements revealed the high dynamics of these soils. Some abrupt changes along the profiles and within the sequence indicated (lithological) discontinuities in the soils. Consequently, soils along such slopes often exhibit a polygenetic character. Although the area is forested, soil redistribution rates appeared comparable to agricultural land. The soil dynamics showed that the entire escarpment is an active morphodynamic domain, notwithstanding the paucity of clear landform record of this activity.