UNIDENTIFIED OBJECT

An incomplete and damaged copper-alloy sheet disc of possible medieval date. This disc measures c198mm in diameter, it was originally flat, c1.3mm in thickness but now has a roughly central fold. About a quarter of the disc is damaged and the edge of this quarter now missing. There were also two small edge fragments recovered, presumably broken off from the main disk, the breaks are worn. One face of the disc appears to have been attached to wood as orange-brown fragments of wood can still be seen across this face, preserved due to the chemical reaction of the corroding copper-alloy. The disc has a decorative boarder of small circular indentations, boarder rivet holes and concentric rings of circular perforations across it.

All of these indentations and perforations have been created by being pushed through from the face without remains of wood adhering to it. The border indentations are c1.7mm in diameter, in one area a line of four of these small circular indentations can be seen heading from the boarder of the disc towards the centre of the disc, they stop when they reach the concentric perforations. The indentations look like small bosses on the other (wood covered) face.

The border rivet holes are also circular and c2.7mm in diameter, they are in places now missing due to damage to the disc or no longer visible due to corrosion. The surviving visible rivet holes are 53mm, 74mm, 68mm and 93mm apart respectively. One small copper-alloy rivet survives and was discovered with the disc although it is no longer in situ. It is formed from a tubular piece of copper-alloy with a triangular shaped head, it measures 12.1mm in length. The head measures 5.5mm by 2.5mm in size and the shaft tapers to a sharp point, is circular in cross-section and measures c2.3mm in diameter.

The concentric circular perforations begin at c19mm in from the edge of the disc. There are seven concentric rings of perforations with a central perforation in the middle of the innermost ring. The concentric rings are c7mm apart, they are fairly evenly spaced. The perforations are roughly circular and measure c4mm in diameter. The perforations of each concentric ring are c4.5mm apart and again fairly evenly spaced.

Also associated with the disc and possibly originally through one of the concentric perforations was an iron rivet, now corroded. It measures 18.9mm in total length, has a roughly oval shaped flat head measuring 7.9mm by 5.6mm in size. The shaft is roughly rectangular in cross-section and has corrosion products adhering to it, making it thicker than it is likely to have been originally, it now measures 4.1mm by 4.7mm in cross-section. This is the only iron rivet found with the disc. It is possible that every perforation in the concentric rings originally had an iron rivet through it. Orange-brown corrosion products do survive around the perforations, however, when tested with a magnet this corrosion does not appear to definately be iron as no magnetic reaction was seen. It is perhaps more likely that this corrosion is due to the wood, indeed the surviving fragments of wood are also this distinctive orange-brown colour.

The function of this unusual disc is unknown, as it appears to have had a back plate of wood it could not therefore have functioned as a strainer. Its decorative boarder indentations and evenly spaced concentric circles of perforations suggest that it perhaps had a decorative function. Helen Geake has examined this disk and knows of no parallel for it, although she has suggested that it is most likely to be medieval in date. This is also perhaps the most likely date as directly above the disc, which was discovered possibly just below the plough soil, a fragment of a medieval lava quern was also discovered (see SF-7FD1F1).