The soil skeleton as a tool for disentangling pedogenetic history: a case study in Tuscany, central Italy

In this paper we show that the study of the soil skeleton (the > 2 mm fraction) can be useful for detecting the presence of paleosols and events that contributed to the development of the present soil mantle. We studied profiles at four sites, all formed on sandstone in Tuscany, central Italy. The bulk density, porosity, mineralogy, organic C, total NH4+-N and effective cation exchange capacity (ECEC) of the fine earth ( <2 mm) display expected trends with depth. In contrast, data for the skeleton fraction show partially reversed depth trends, suggesting the occurrence of paleoevents, such as solifluction, that are considered to date from the Wurm glaciation. It is inferred that, because the skeleton is relatively inert physically and chemically, it retains a memory of the pedogenetic history better than does the fine earth. The reconstruction of episodes leading to the present profiles would not have been possible from soil morphology or analyses of the fine earth alone.