Roddon

A roddon, also written as rodham, roddam or rodden, is the dried raised bed of a watercourse such as a river or tidal-creek, especially in The Fens in eastern England.

[3] The origin of the raised nature of a roddon is debated; some writers suggest this is due to a silt build-up during marine incursion.

Astbury agrees that later writers have adopted Fowler's spelling though he still maintains that fenmen call such silted-up old river beds rodhams.

[nb 11] The Nordelph peat, which covers a large area of fenland, including most of the Ely district, began forming around 4000 BP.

[25] The archaeologist Major Gordon Fowler explained these are due to the extensive drainage of the fens, and "differential shrinkage" of the silt bed and the surrounding peat.

[27] The cause of the shrinking is due to a combination of drying out, trench cutting for peat-fuel, biological oxidation and surface burning associated with arable farming.

[22][29] Dinah Smith agrees with Fowler, suggesting that the raised nature of the silt banks are due to the "subsidence" of the surrounding area, mainly caused by human activity, such as agriculture and drainage.

[24] In recounting the building practices of the local area, Astbury notes that major structures such as the monasteries at Ely, Thorney and Crowland were built on islands or ridges.

[31] For example, the village of Little Thetford, 5 kilometres (3 mi) south of Ely, lies at about 5 metres (16 ft) above sea-level, and sits largely on an island of Kimmeridge Clay, a Jurassic shallow-water shelf-sea deposit.