The Car Dyke was and to large extent still is, a ditch which runs along the western edge of The Fens in eastern England. It is generally accepted as being of Roman age and for many centuries, to have been taken as marking the western edge of The Fens. There, the consensus begins to break down.

Likely purpose

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In the eighteenth century, William Stukeley described it as a canal, used for transporting goods and that idea is still promulgated but is demonstrably very unlikely. It has causeways of never-disturbed ground crossing it and it passes in gradients, up and down the sides of slight ridges. It is said to be a catchwater drain and so it undoubtedly is but only in parts. The southern half of its passage through Lincolnshire and its northern end, near Washingborough, are accepted as having had a raised bank on each side. That on its upland side was not a feature well adapted to a catchwater drain.

The seemingly inevitable conclusion, though not one reached by everyone, is that overall, it was designed primarily as a boundary, that parts were adapted to serve also as a catchwater drain and that parts, such as that near Peterborough, are a little older, were designed as a catchwater drain and were later incorporated into the overall boundary scheme. It is possible to trace features which could be interpreted as boundaries all round The Fens which are either of Roman date or natural. The exception is in the south-east where the landscape was manually strip mined for phosphate so destroying any evidence, before the days of detailed mapping and aerial photography.

References

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• Phillips, C.W. ed. The Fenland in Roman Times Royal Geographical Society (1970)
• Macaulay, S. & Reynolds, T. Excavation and Site Management at Cambridgeshire Car Dyke, Waterbeach (TL 495 645) in Fenland Research No 8 (1993) ISSN 0268-263X