Soil erosion is a natural geomorphological process that occurs on most of the world’s land surface, with the principal exception of those areas on which soil eroded from elsewhere is deposited. Since soil erosion rarely occurs in dramatic events, perception of its seriousness, measurement of its progress and persuasion of the need to take ameliorative action has been a long process. A fundamental distinction is made between natural or geological soil erosion – a phenomenon that forms an integral pathway in numerous biogeochemical cycles – and rates that are accelerated by human activity, and it is accelerated erosion that has received most scientific attention. Such attention is not new, however. Ancient Greek and Roman observers of the natural world commented on the effects of such human activities as agriculture and deforestation on soil loss.