Archive

Posts Tagged ‘Mills’

A medieval weir. Part 1

November 11, 2011 2 comments

river scene

When people in medieval times looked at urban rivers, like the River Great Ouse in Bedford, they saw something quite different from what we see today. Not so much a picturesque scene with pleasant walks along embankment promenades, past riverside gardens and ornamental bridges. That was a creation of the Victorian and Edwardian eras. No, what they perceived was more basic, more elemental. The river was seen and experienced, amongst other things, as a great flow of energy moving slowly and inexorably through the town.

It was a flow of energy, moreover, that could be harnessed and put to use. From middle-late Saxon times on, in many river towns throughout Britain, mills were built next to the river – larger than those on small streams out in the country. Artificial watercourses were cut to serve as headraces and tailraces, taking the flow of water from the river and back into it again. In some cases, massive stone weirs were placed across the river to create the head of water to power the mills. These were such important features – so vital to the urban economy – that towns like Warwick, Ware and Wareham were actually named after their weirs.

Surprisingly few people today know in which direction their local river flows. Which way is upstream and which downstream? This knowledge, once so crucial, no longer has much significance for town inhabitants. Other flows – such as those of electricity, gas and oil – now provide most of the energy that the town needs. But that does not mean that we should forget how important the flow of water was to people in the past. The river environment is full of clues as to how people once interacted with the energy of flowing water – how they channelled, shaped and diverted it for their own purposes and projects.


Computer screenshot of aerial photo taken when the river was low and clear in July 2006 (©Google 2010, ©Tel Atlas 2011 and ©Getmapping plc 2011) with detail of the relevant part of the image. Direction of flow is from left to right. Ignore the modern path that coincidentally almost aligns with the feature: this was built a few years ago and is unrelated

Take Bedford for example. A huge archaeological feature has come to light. The feature takes the form of a linear band of riverbed vegetation crossing the River Great Ouse diagonally from the north bank to a small island on the south side. The ‘underwater cropmark’ is 40m long and 3m wide, visible on Google Earth (on a 2006 aerial photo accessible through the ‘historical imagery’ function) from 1km up.
Normally the feature is not visible from the ground, with the water being too high and too murky. But this year the exceptionally dry Spring lowered the river, and short rainbursts in June significantly improved visibility. For a period of about a month, and for the first time in my lifetime, the feature was clearly visible from the river bank.


View from the north bank, looking south-east, June 2011. The feature appears as a broad band of underwater plants running across the middle of the picture


View looking straight down from a boat immediately above the underwater feature. The river weeds in question are known by anglers as cabbage lilies or lily pads – more formally as the submerged leaves of Nuphar lutea (Yellow Water-lily).

This is not the first time that the feature has been noted, however. It was described and mapped by local historians in the early 20th and late 19th century, and variously identified as a former causeway, barrage, weir or dam. In 1926 Farrar stated that “when the water is clear it is possible to trace a broad band of weeds at the bottom of the river, marking the course of the barrage which crossed the river obliquely in a south-westerly direction to the small island…”


Map of the underwater feature drawn in 1906, when it was visible as a broad band of weeds (Goddard 1906).


An earlier map by Hurst in 1859 shows it as the foundation of a submerged stone wall (Hurst 1859). Direction of flow is from left to right.

The earliest reference to the feature is by a former mayor of Bedford called George Hurst (see map above). He wrote in 1859 that part of the foundation of a stone wall, ten feet wide, could be seen crossing the river at low water. He mapped its position for us, and said the wall was the remains of a stone barrage in existence up to 1774, when it was demolished and the stone re-used for building works. The submerged wall or barrage had previously been utilised for mooring barges, though its original purpose was probably forgotten even at that time.

It seems, then, that the broad band of weeds visible today marks the course of a former large stone feature which crossed the river to the small island, already submerged when it was removed in the late 18th century as part of river navigation works. Quite why lily-pads should find such favourable rooting conditions along the line of the former stone feature is not fully understood. But it is well known that growth of vegetation on dry land can be influenced by archaeological features: the same must surely be true underwater. The question remains as to what the original function of the river wall was. The idea that it was once a weir (submerged by later embanking and deepening of the river) is supported by its diagonal orientation relative to the current, reminiscent of many other weirs both ancient and modern.

Part Two of this post will investigate the relationship between the weir and a kilometre-long late Saxon boundary ditch around the southern part of Bedford. Although the two features are not contiguous, the relation between them can be explored, it will be argued, through patterns of flow…..