In 1996, the first SHARP season, evaluation test pits in the river valley area known as the Reeddam revealed that below the 8-10 inches (20-25cm) deep top layer of humus, is a mysterious white marl layer ranging in depth from 4 inches (10cm) along the southern side, to some 2 feet (0.6m) at the northern side by the river. A theory offered up at the time was that the marl had been laid down by long-term inundation.
This idea failed to hold water as such a process (the laying down by filtration of fine particles suspended in continuously slow moving water) would have had to occur over a very long period of time - beyond the bounds of the known and recorded history of the area in question. The excavations also revealed that the marl was sealing Iron Age and middle to late Anglo-Saxon artefacts and other archaeological evidence. Therefore any such expanse of open water could not have existed until after, at the earliest, AD 900-1000. The questions remained: when, how and why was the marl deposit laid down?
A short recapulation of the known historical evidence on the Reeddam would help to place the area in its chronological context; the following five paragraphs are part of an article (updated) published in the first SHARP Report (Hammond & Barnett 1996).
The first documentary evidence for a sixteen-acre pond and reed bed at Sedgeford is in the manor bailiffs account roll for 1278/9 (NRO/DCN/60/33/6. (Most account rolls prior to 1272 were destroyed in a fire of that date). Amongst the many entries on this roll are several which refer to considerable works undertaken on water courses, dykes and sluices in and around the manorial site. This account also shows that the pond and reed bed were already in existence, as in this year a new or refurbished ‘dyke’ or dam to the east of the manor is mentioned, which corresponds to the present, road topped, north-south causeway immediately to the east of West Hall manorial site. The reed bed (arundinetum - also given as stagnum (pond) in the account roll) was cleaned and renovated and a new watercourse opened near it, which led down to the bridge. Almost certainly the ‘new’ watercourse was in fact the canalization of the river, resulting in the isolation of the arundinetum from the river and the possibility of water management that is still visible today. The canalized section started at the eastern end of the reed bed and led the river down its northern edge to drive the Great Mill, a water mill then existing on the manorial site. Previous to this the river had probably run through the lowest part of the valley, fed by a spring from the Chalk Pit. This was now controlled by a sluice in the southwest corner which was closed when there was the optimum depth of water in the Reeddam, around 2½ feet (75cm), and the flow was diverted into a ditch leading down to the river at the eastern end of the Reeddam, letting the overflow into the the river.
In 1285/6 the stagnum was restocked with 1200 pike, and in 1325/6 it was cleaned at the cost of 28 shillings – calculated to be a minimum of 130 man-days of labour, based on daily wages of that date. The reason for cleaning what was, in effect, a reedy lake is not mentioned in the account rolls, although it is not difficult to deduce one. In order to maintain stocks of pike and yet to commercially farm reed, an appropriate balance between open water and reed bed is necessary, as well as a water depth suitable to both and. the option of raising the water level is naturally limited by the height of the surrounding banks and dykes. Such limitations eventually pose a problem, because optimum reed growth necessarily creates dense thickets of root and stem. Year on year, the level of the reed bed rises eventually to form peaty or marshy marginal land inimical to large fish such as pike and, without water-level control and regular cutting, would naturally progress from reed bed to woodland. (Madgwick & Hawke 1996 pp5-7). It is in this context that the very costly ‘cleaning’ operations of 1278/9 and 1325/6 must be understood.
When the Manor was first farmed out to lay tenants in the 1420s windmills had been replacing watermills for two centuries, reducing the need to protect the flow of water in rivers. This meant that much of the maintenance of the sluices controlling the flow of water and the costly cleaning of the pond would have been some of the early economic cutbacks, and the reed beds would have spread to fill the whole area. Then, with the advent of clay tiles, the growing of reeds for thatching became less profitable; without cutting, the beds would have silted up and become invaded by coarse grasses, with the result that two hundred years later the Parliamentary Survey of 1649 (NRO/DCN/52/1) describes this once highly profitable area as ‘a peece of course reedie ground, the common river on the North and the highway from Snettisham on the west conteyning by estimacion 8 acres at 10s per acre amounts to £4 p.a. However the actual rent being received for it was set down in a lease of 1637 for 21 years as being …… for and in consideration that the said reed ground is so poore a thing as noe man will take the same at a greater rent than £1 6s 8d and 1 comb 3 bushels, 3 pecks of wheat (value 31s) and 3 bushels, 3 pecks of malt (value 14s). (NRO/DCN/47/4/ff91-3) This made a total rent of £3 11s 8d.p.aPlease click here to download full report.