Greater Gabbard Windfarm, Sizewell

Greater Gabbard Windfarm, Sizewell

An excavation has been carried out in Rosary Field, Sizewell, as part of a programme of archaeological work, which was a condition of the planning consent to construct the onshore component of the windfarm, funded by Greater Gabbard Offshore Winds Ltd.

The excavations have so far revealed the remains of timber buildings based round earth-fast posts and clay floors, small ditches (indicative of corrals or animal enclosure) and the site of three large external ovens. All of the archaeological features are likely to be broadly contemporary and the narrow date range of the finds, which fall between the 12th-14th century, suggests a short period of occupancy. The site appears not to be within the medieval urban settlement of Sizewell and may be an isolated farmstead or agricultural complex.

The size and depth of the postholes suggest that the timbers they held were large and part of substantial buildings including a possible barn. The barn building is c.16m long and at least 5m wide. It has an aisled ground plan, constructed around paired arcade posts. The outer walls would not be load bearing and as a consequence would not leave any evidence in the ground but at the west end a vestige of a clay floor survives. At this period posts set in the ground was old technology and house construction had moved on to box framing, however agricultural building continued to be built around earthfast posts.

Similarly the size of the ovens indicate that these are not simple domestic structures. They were situated outside the buildings and stoked from a large pit in front of a double flue. Only the oven floors remain, made up of burnt clay and consolidated with pebbles. Over the floor there would have been a domed chamber made of clay over a wattle frame, this has been destroyed but fragments of it have been found along with the charcoal from the oven firing within the stoke-pit. The function of the ovens is as yet unknown but the degree of burning indicates that they were fired at low temperatures suggesting that they are likely to have been bread ovens or corndriers, but analysis of the charcoal in the stoke-pit should reveal this.

The site is just to the south of Leiston’s Wet and Dry Commons which, until the dissolution of the monasteries in c.1538, belonged to Leiston Abbey as the manorial lords. It is possible therefore that the site could also be the property of the abbey and is part of a monastic grange where grain from the Abbey’s farms and collected as tithes from tenant farmers would be processed and stored.

The general quality of the pottery also indicates that the inhabitants enjoyed relatively high status. 
 
A broad natural channel runs across the middle of the site which is an extension of the fenland grazing wet common known as Sizewell Belts. Initial investigations show that the channel had become largely infilled by silts and blown sands by the time that the site was occupied. Peat deposits at the base of the channel do survive and study of these will give us an indication of the ancient landscape.



Climatic changes known as the Medieval Warm Period were occurring at this time and rising water level and coastal erosion meant that Sizewell, which had a greater population than Leiston in the medieval period, and held a market (an indicator of urban status), was being lost to the sea. It is possible that the silts within the channel hold evidence of these events.

Phase 2

A second phase of archaeological excavations in advance of the onshore works for the Greater Gabbard Wind Farm at Sizewell found the remains of an early medieval boat. The boat which was probably a small inshore fishing vessel had been broken up sometime between the 12th and 14th centuries and parts of the hull re-used to create a timber lining for a well. The waterlogged conditions has ensured that the planks are very well preserved and this will allow experts a rare opportunity for study.

Although much more modest the boat was constructed using the same techniques as the great Sutton Hoo ships. It is clinker built with the planks joined together along their edges with closely spaced iron rivets before being attached to the boat frame with wooden pegs; and there is evidence of ‘luting’, wool like fibres between the planks to seal the joints. It is hoped that tree-ring dating will provide an accurate date for the boat.

 

The site would have been part of the property of Leiston Abbey and is located outside Sizewell, which was an urban centre in the medieval period. The site follows the edge of a low-lying channel, which would have formed a fresh water lagoon and would have been the focus for industrial activities. Evidence of timber buildings, hearths and wood-lined water pits have been found clustered at the channel’s edge. Hemp retting for the manufacture of linen and rope is known to have taken place in the area; this is a noxious process as there is documentary evidence of practitioners being fined for fouling the water.

Finds include a wide range of pottery, dating from the 12th-14th centuries, part of a wooden platter, animal bones and various personal items such as buckles and clothing fasteners. Fishing hooks, weights and fish bones have also been found.