 The Nordelph peat, which covers a large area of fenland, including most of the Ely district, began forming around 4000 BP.Sampling of roddons in the area has confirmed that they were formed from the mid– to late–Holocene age — 6000–2000 BP.The raised and layered banks of silt in a roddon contain mostly estuarine foraminifera and ostracods, which suggests that the silt was deposited through tidal processes.