Greyfriars, Dunwich – Coralline Crag in action

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Greyfriars, Dunwich – Coralline Crag in action Suffolk is not naturally blessed with abundant local building stone, although clunch in the western part of the county, septaria in the east and widespread flint rubble have traditionally been used. However, a rare opportunity recently arose to record the use of Coralline Crag.

Coralline Crag ‘Rock Bed’ has been used locally in coastal Suffolk as a building stone mainly from the 14th to 16th Centuries. This Crag is unique to Suffolk, outcropping from just north of Aldeburgh to Gedgrave with smaller inliers, as at Sutton. With the possible exception of Orford Castle, the ‘Rock Bed’ does not seem to have been used by the Normans, but for lesser structures on farms and in walls (e.g. in Quay St and the churchyard at Orford) and for repair work. More substantially, sawn blocks were used for a 15th Century extension to the chancel at All Saint’s, Eyke. But perhaps the best examples are to be found at St John Baptist, Wantisden and St Peter’s, Chillesford, where the towers of the churches were built of sawn blocks during the mid-14th Century. Blocks used for recent restoration at Chillesford church came from Crag Farm, at Sudbourne, some 5 km to the east.

In March 2013 a unique opportunity arose to observe the extraction and use of Coralline Crag from Crag Farm for major repairs and restoration of Greyfriars boundary wall in Dunwich, ‘Suffolk’s lost city’. Crag Farm, is of considerable historic interest and visited by many field groups to examine the 4 million year old Sudbourne Member of the Coralline Crag and the so-called ‘Rock Bed’. In the farm-yard over 150 m of in situ Rock Bed face is used as ‘walls’ to pens, stack-yards, barns and sheds. Of note are the clear 3D medium- and large-scale cross bedding sedimentary structures, with bryozoan shell avalanche at the base of foresets. The adjacent Crag pit, a SSSI, the largest Coralline Crag pit remaining, c.150 m long, c.4 m high, is still used as a stack-yard.

Greyfriars friary became home to the Franciscan Order shortly after the Order reached England – Henry III gave some land in the north-eastern part of the town in 1230. Within 60 years, after a series of great storms, it had been abandoned because of the coastal erosion by which the city was ‘lost’.

A new site, to the west of the town and where the rampart was levelled in 1290 to provide access to the town, took some 20 years to complete, in 1307.

The boundary walls date from this time. The friary was one of East Anglia’s main Franciscan centres and Dunwich’s leading religious house. After the Dissolution (the friary closed in 1538) much masonry was removed by builders; the main building became a private house. After several incarnations, including a summer home with civic hall and prison cells, it was largely demolished in 1815, leaving only a ruin.

Much of the perimeter wall has recently been repaired (Plate 15), walls to the north, south and west mainly with flint rubble. The clearing of brush, ivy and other overgrowth away from the wall has exposed the fabric in all its glory; surprises include a limestone gargoyle set into the south wall, rediscovered after many years! The west boundary wall and main arched entry gate contains the same flint, limestone, septaria and many of the ‘exotics’ seen in St. James’ Church – chalk, granite, dolerite, gneiss, quartz,

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quartzite and sandstone, much of which was imported as ballast for trading ships or recycled from earlier buildings (see: Dixon, 2005). However, the east wall, facing the sea on the cliff top, contains a large amount of Coralline Crag, now well displayed – it is for this wall that the Crag Farm crag was used.

Excavation work at Crag Farm, originally planned for late 2012, was well behind schedule because of the wet winter weather. As it was, excavations took place on a very wet Friday, 8 March, 2013, with waterlogged ground, a flooded pit, and temperatures barely above zero. Some blocks were sawn in situ, while some were first loosened by drilling. The blocks, around 5m3, from two parts of the quarry face, were removed to Universal Stone’s yard for dressing. The last six of the c. 20 pallets and 3 m3 bags were loaded on Tuesday, 12 March, with a good covering of snow on the ground.

Some stone was dressed in the yard – sawn into blocks, some sized to match originals, but much dressing was done on site. Off-cuts and trimmings were used as fabric infill to minimise wastage. One frequent comment from the masons was that the Coralline Crag was very soft when fresh. However, it does harden up when exposed to air as moisture evaporates and salts precipitate. Indeed, the Crag had hardened appreciably within only a few days.

Also used with the Crag in the east wall were sundry cobbles of limestone and sandstones brought in from the yard – they should ‘blend in’ nicely with the existing ‘exotics’ and pieces of dressed stone from the monastery fabric.

Figure 1. Architect Tim Buxbaum and Contract Supervisor Simon Thulborn by the Coralline Crag wall at Greyfriars. The newly sawn block is 60x20x20cm; the average size of ‘old’ blocks is c.60x20x15cm, but is very variable.

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Figure. 2. Repairs in progress.

Formerly owned by Suffolk County Council (SCC) and as part of Council policy of transferring such sites to the local community, the site passed over to Dunwich Greyfriars Trust at the end of March, 2013. The Trust was established in February, 2012 to own and manage the Greyfriars monastery and wood site. The charitable group intends to encourage biodiversity, maintain public access to the current buildings and enhance the education and recreation benefits provided by the site.

The repair work, completed at the end of June, was funded by English Heritage (£186,000) with additional funding from SCC, and overseen by Suffolk-based architect Tim Buxbaum. Some parts of the east wall were left, for example at the south end where it had been knocked down during the war to make way for a gun emplacement. The stone masons were Universal Stone of Battlebridge, Essex, a leading specialist contractor in building conservation and restoration, with an impressive list of clients in London, East Anglia and the south-east, under Contracts Supervisor Simon Thulborn.

The site lies within Suffolk Coast & Heath AONB and is listed as an Ancient Monument. It forms part of GeoSuffolk’s Dunwich geo-trail – a free leaflet can be downloaded from our web-site: www.geosuffolk.co.uk Reference Dixon, R.G. (2005). Magazine of the Geologists’ Association. 4 (2), 20–21.

Roger Dixon The White House, 7 Chapel Street Woodbridge Suffolk IP12 4NF

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R. Dixon Plate 15: Roger Dixon standing in front of the newly repaired boundary wall of Greyfriars monastery which uses Coralline Crag (pp. 87 and 92).