Reprinted from Newsletter 126, dated 2008 August

What is Glastonbury made of?

Susanna van Rose

A woman closely examines a stone wall's surface.

“It’s permanently in here,” says Susanna as she fishes a jeweller-style magnifying glass from her shoulder bag. In the Abbey wall she finds a fossilized belemnite, an extinct squid-like sea animal. A geologist at the Natural History Museum specializing in building stone, Susanna again lives in her native Glastonbury and edits Rockwatch, a magazine about geology for children. Photo by Jim Nagel

A select group of Glastonbury Conservation Society members met in the carpark behind St Mary’s church hall in the week of the Glastonbury Festival, to discuss the kinds of stone purloined from the Abbey ruins for building in Glastonbury.

There, the old carpark wall facing the new Cavendish Lodge displays the higgledy-piggledy masonry that characterizes stone walls built of second-hand materials. Here we recognized Doulting Stone, Lias*, Tor Burrs and the conspicuous tufa with which the Abbey was vaulted.

Especially interesting was the tufa, material deposited from lime-bearing springs similar to the present-day spring in Dulcote, a kind of spring that must have been more abundant in centuries gone by. The material was popular for vaulting in medieval churches because of its spongy, lightweight nature, combined with strength, coherence and ability to be cut to shape.

The profusion of fossil belemnites in the Tor Burrs was explained as being the vomited-up material from the stomachs of plesiosaurs and ichthyosaurs, marine creatures that had largely lived on eating the soft parts of belemnites (relatives of the modern squid), but were unable to digest the hard parts they swallowed. This led the group to the Abbey carpark to locate and identify a bone of one of these predators, preserved in a similar wall outside the Abbey (the precise location is a secret), along with more yet more vomited belemnites.

On the way, St Mary’s church, built 1939–42 of Bath Stone, was examined in detail, and the natural stone was compared with the later work of the church hall in reconstituted stone. The versatility of Bath Stone was noted: the church shows it in use as exterior paving slabs, large monoliths for the entrance steps as well as smooth ashlar work and more rusticated styles of building, as well as its capability to be carved to fine detail in statuary. The overland journey from the Bath quarries to Glastonbury was not feasible until the arrival of the railway, so use of this stone can be discounted in any of the town’s older buildings. A characteristic feature of Bath Stone is the lacy, milky-coloured cement that holds together the rounded ooliths (looking like fish roe).

The buildings which till recently had been Abbey School and prior to that the St Louis convent and its school were admired, and the difference between the very fine stonework of the Lias on the older northern building (now labelled Naish House) were compared with the more modern Lias work on the school part nearer the church.

Next port of call was the Natwest bank, where we did not loiter long for fear of being thought to be “casing the joint”. The warm colour of the Ham Hill Stone façade was noted as well as the tendency for this stone to weather out along the dune-bedding layers. This weathering characteristic has led to recent stone replacement work around the doorway.

Problems of sympathetic repair and maintenance of old stonework were discussed outside the George and Pilgrim (Doulting Stone, now almost totally obscured by render), and the Tribunal, where a layer of Lias just above pavement level was discussed as being a possible damp-proof course to the wall.

The afternoon ramble through 180 million years of Earth history terminated at the Avalon Club, which is largely built of a stone from the Mendips, the confusingly named Dolomitic Conglomerate or Draycott Marble. The attractive stone, which colours the walls of so many lovely buildings in Wells as well as the imposing city walls, was likened in origin to slope breccias in the modern-day Valley of the Kings in Egypt. Likely locations of quarries for this stone in Wells have now been built on, though one may be still visible in the woods on Tor Hill. A few buildings at the top end of Glastonbury High Street use this stone.

Roofing material other than Welsh Slates (which did not arrive till after the railway) and locally-made clay tiles were also discussed. The possibilities were Delabole Slate from Cornwall, or fissile layers from local limestones. A rare location where old limestone roofing slates are still to be seen in use is the old Park Farm buildings at the far end of Benedict Street (formerly called Station Road), but this was not visited. The merits of Glastonbury bricks and tiles, products of three or more brickworks along Wells Road, were discussed in passing. The importance of mortar in brick and stonework, and use of burnt material in local mortars led to interesting discussion.

In recent decades, stone arrivals in Glastonbury include York Stone paving slabs in the Market Cross area, and most recently, two large glacial boulders of granite-gneiss which have been installed in the Morrison carpark. These last could not have originated nearer than Brittany or the northwest Scottish Highlands, or less likely, Anglesey. These highlight the ongoing trend for ever more far-flung materials to be used, as the world continues to come to Glastonbury.

© 2008 Susanna van Rose