Stonelayer

A stonelayer, or soil stonelayer, or stone line, is a three-dimensional subsurface layer, or soil horizon, dominated by coarse particles (>2mm), that generally follows (mimics) the surface topography (Sharpe 1938). A stonelayer occupies the basal horizon of two-layered soil biomantles (Paton et al. 1995; Schaetzl and Anderson 2005; Fey 2009; Wilkinson et al. 2009). A stonelayer may be one stone thick, and thus appear in a trench or pit as a "stone line," or it may be several stones thick and appear as a "stone zone" (Johnson 1989). The gravel components of stonelayers may be compositionally variable, and while many are lithic clasts, often of quartzose composition, others may be metallic nodules and concretions of iron and manganese oxides, human artifacts, snail and clam shells (in highly calcareous soils), precious and semi-precious stones, or some combination thereof (Aleva 1983, 1987; Johnson 2002).