The conversion of bedrock into weathered regolith is governing the balance between soil formation and soil erosion, the withdrawal of atmospheric CO2 and the supply of nutrients into ecosystems. Processes controlling soil weathering front is central to better understanding the origin and evolution of secondary minerals, which are important players in terrestrial biogeochemical processes as they provide the largest part of the reactive surface area of soils. This session deals with the onset of soil formation deep in the weathering front where water, oxygen and acids convert bedrock to saprolite. The often observed correlation between erosion at the surface and chemical weathering at depth requires that these two processes are linked through feedbacks at the weathering front. We are inviting contributions that explore the way this Earth surface interface advances, and the chemical, mineralogical and geomorphic expressions of these links. The session aims at bringing together field of soil sciences (soil biology, soil chemistry, soil physics, pedogenesis and applied geochemistry) helping to better understand the mineralogical (trans-)formations, organo-mineral associations, the possible role of fungal and bacterial weathering, fluid-solid interaction and the feedbacks between erosion and weathering.