3 new biota and extinction of others, and extensive soil erosion reaching almost catastrophic proportions have led to desertification of many upland areas and abandonment by local populations. The role of climatic change as opposed to deforestation and sheep grazing in creating these new environments has proved a further issue of great controversy. While our understanding of historic environmental changes remains inadequate, our knowledge of processes that are modifying the present-day landscape is also sparse and selective. Little is known of active periglacial processes, slope...