CHEMICAL WEATHERING AND SOIL FORMATION FROM MULTIPLE PARENT MATERIALS IN A COMPLEX REGOLITH, SHALE HILLS, PENNSYLVANIA
In this work, we report on the geochemical evolution of soils developing through complex colluvial stratigraphy in a swale of a small, shale-bedrock watershed in central Pennsylvania (Shale Hills CZO Experimental Watershed). We find that the bedrock-regolith contact is marked by a thin (several cm) saprolite with distinct gleyed mottles. Above this saprolite in the swales is one or more deposits of well-sorted 0.1 – 2 cm angular shale chips, interpreted as periglacial sorted talus (grèzes littés) that can exceed 2 m in thickness. We present preliminary grain size and elemental depletion profiles through these parent materials to illustrate the degree of chemical weathering and pedogenesis. The diverse transported parent materials provide significantly different textural and hydrological pathways for pedogenesis, which we contend should have a first-order feedback on weathering profile geochemistry and long-term hillslope form.