Blenheim Palace
In July the STONE-WORK team visited Blenheim Palace, Oxfordshire, where we met with members of the Blenheim-Oxford Partnership, Sterling MacKinnon III, Richard Grove (University of Oxford), Chris Monaghan (Clerk of Works, Blenheim), and Aimee Akinola (Project Intern, Blenheim), and learned about their work on high-tech heritage restoration.
Window Jambs: Cross-bedded Burford/Taynton
Materials & Techniques:
One of largest, most expensive, and fraught architectural endeavours of eighteenth-century Britain, Blenheim Palace (1705–1722) is a highly complex building. A variety of stone types are employed externally and internally, both from local Oxfordshire quarries as well as much further afield. The exterior of the building shows much patching and repair over the centuries, while a copperas wash has been applied to the stonework, further complicating identification. Close eye-level examination of the building’s fabric allowed us to identify several of the stone types used, and cross reference these findings against archival evidence in the original building accounts.
Cornbury Stone with a lag of fossil echinoid shells.
Cornbury Stone:
Large amounts of Cornbury Stone, with distinctive urchin ‘hooks’, were identified in the ashlar walling of the main pile (East and South fronts in particular) and in the giant orders of the entrance front in the Great Court. Cornbury Stone from the Clypeus Grit was quarried at Cornbury Park, near Charlbury, a few kilometres North of Blenheim. This is a coarse grained oolite with fossil fauna dominated by sea urchins (echinoids) which makes this a very distinctive stone for this region and indeed Britain and Ireland in general. These fossils are seen as sections and partial sections through shells, often appearing as hook-shaped inclusions. Traces of ornamentation typical of echinoids can often be discerned on the shells. The Clypeus Grit is a member of the Middle Jurassic Salperton Limestone Formation and normally is too rubbly and fissile to be suitable as a building stone. However, it seems that the stratum at Cornbury is unusually well-cemented and hard.
Giant Order, North Front: Cornbury Shafts, with urchin ‘hooks’.
Burford/Taynton Stone
Burford Stone was also used extensively at Blenheim Palace as ashlar walling (North front in particular), window dressings and for the pilasters on the East front. Burford stone is a high-quality freestone from the Taynton limestone formation of the Great Oolite group. The stone is a yellow to brown, medium- to coarse-grained, shelly, oolitic calcarenite with pronounced cross-bedding which gives a striped appearance, sometimes described as ‘streaky bacon’. On close inspection, the ooids weather out giving the surface the appearance of pin-pricks. The stone employed at Blenheim Palace came from several quarries around Burford, in north-west Oxfordshire, including Taynton, Kitts Quarry and Barrington, though it was commonly referred to in contemporary documents as ‘Burford stone’, without distinction. The thicker layers at the quarries at Taynton in particular yielded blocks up to two metres in height, which could be cut and shaped into large Ashlar blocks or window and door surrounds.
A darker variety of Burford stone was used as a weatherstone for copings, bases, and perhaps capitals of columns and pilasters. This likely came from the Taynton quarries as this variety possessed the greatest resistance to weathering due to its iron content, which resulted in an ochre hue. The stone quarried at Upton was pale and finer in texture, producing a good cutting edge, and so was more suitable for internal work and sculpture.
West Corridor, basement level: Cross bedded and ‘tilted’ bed Burford
The Great Bridge on the northern approach to Blenheim.
Several of the monumental structures in the parkland at Blenheim also provide interesting insights into the different stone-work techniques and materials employed.
Bartholomew Peisley’s account for September 1706 (BL Add Ms 19,593) for masonry work done on the ‘Engines House, Being part of the Bridge of the Approach to the North front of Blenheim’ details the relative costs for different types of work in Burford stone:
3064:6 feet of Straight axed Burford ashlar at 6 pence per foot, £76:12:3
1597:2 feet of Circular arch head of Ax’d Burford at 10 1/2 pence per foot, £69:17:6
650 feet of Rustic ashlar in the Front Arches of Ax’d Burford at 10 1/2 pence per foot, £27:01:8
566:4 feet of Straight Ax’d Burford facia.t 7 pence per foot, £16:10:4
The upper levels, at least those on the east side were not complete until 1721-3. The estimate by William Townsend and Bartholomew Peisley (III) of September 1721 (Green, 1951, p.312, Blenheim MS, F-I-49) specifies ‘Headinton freestone Ashler and other meteriale as specified on the other side’. The unusual ‘Beehive’ frosting on the westside is referred to as ‘frost work’ and was not to be done on the east side.
Melanie Hayes, with geological input from Ruth Siddall