The Fens—An Example of Large-Scale Anthropic Transformation of a Lowland Landscape

Abstract

The Fens is a low-lying, near-coastal terrain in the eastern part of England. The Fenland topographic basin is the product of glacial and periglacial erosion during the Pleistocene, whereas in the Holocene deposition of peat, silt and clay occurred. Peat prevailed in the southern part of the Fens (Black Fens), whereas in the north the surface was underlain by fine-grained marine deposits from repetitive Holocene transgressions. In mediaeval times large-scale engineering works on Fenland waterways commenced, aimed at gaining agricultural land, improving navigation and reducing flood hazards. They were intensified in the seventeenth century and led to the complete transformation of the original fluvial network two centuries later. These direct interventions, coupled with secondary effects of peat desiccation and wastage, brought about significant geomorphic consequences. These include widespread ground lowering (subsidence), locally by as much as 2.5 m in 130 years, the emergence of former river channels as topographic highs (roddons), abandonment of many original fluvial tracts, and an increase of flood and wind erosion hazard.