Guiting Quarry
A visit to Guiting Quarry, Gloucestershire, 25 Jul 2024
There has been a long history of quarrying in the area of Temple Guiting and elsewhere in the vicinity, probably dating back to Antiquity. Certainly other stones from the Birdlip Limestone Formation and quarried in the Cotswolds area (i.e. Pea Grit, Painswick Stone) where in use from an early period. They continue to be used today as walling and building stone and also as restoration stone for the numerous historic buildings in the broader Cotswold area and at places such as Blenheim Palace in Oxfordshire.
Guiting Stone is worked from the Cleeve Cloud Member of the Birdlip Formation, a Middle Jurassic (Aalenian) oolitic limestone. We were able to visit the active Guiting Quarry at Coscomb (SP 079 304), operated by Johnston Stone, in July 2024. Here they work the Cleeve Cloud Member for two varieties of stone, Guiting Gold and Guiting Cream.
1. The north quarry face at Guiting Quarry showing the relative positions of the quarried Yellow and white beds (Cleeve Cloud Member) at the base of the quarry, and the overlying Scottsquar Member of the Birdlip Limestone Formation. The latter formation is not quarried.
The two stones from these strata have freestone qualities, meaning that they can be cut in any direction and have no preferred planes of weakness. Until relatively recently, the Cleeve Cloud Member was simply known as the ‘Lower Freestone’ with the quarried beds named as the ‘White and Yellow Freestones’ and these terms are still useful for describing the buildings stone members. The Yellow Freestone (Guiting Gold or Yellow Guiting Stone) is the lowest layer and is a coarse grained, ooidal, cross-bedded, grainstone with abundant shell debris and a distinctive golden yellow in colour imparted by the iron oxide mineral goethite. It is a striking building stone and the geologist William Arkell, clearly not enamoured with it, described it as ‘an offensive chrome yellow colour’. These beds are around 12-14 m thick. The overlying White Freestone (Guiting Cream) is a coarse grained, cross-bedded, ooidal-grainstone with very minor shell debris around 16-20 m thick. Both these units contain few fossils, and where present these are predominantly broken shell fragments. However a few fossils have been found at the base of the Yellow Freestone including the scallop Propeamussium pumilum.
2. Sawn blocks of Guiting Stone, showing the colour contrast between the Yellow and White varieties.
The British Geological Survey Memoir for this area also notes the occurrence of a reef knoll composed of coral-rich carbonate mudstones at the junction of the Yellow and White Stones at nearby Oathill Quarry (SP1028 2894) and that this surface shows signs of emergence and karstic weathering – essentially the dissolution of the surface opening up fissures and miniature caves. Neither reef nor hardgrounds were observed at Guiting Quarry but there is good evidence of karstification at this level. Flowstone-lined fissures are evident in both the quarry floor and observed encrusting some of the quarry faces. Fissures appear to be linear and follow jointing (which is just off vertical) and travertine deposits may define the face of quarried blocks.
These calcite-crystal lined, vuggy karst features are used for decorative effect by the masonry firm Wrights of Camden who operate from the quarry site. This feature is tolerated in wall stone but is avoided in high quality block.
Block size is typically 1.5 x 1.0 m, and blocks are often tapered, due to the geometric effect of the cross-bedding in the grainstones. This has earned them the name of ‘horse’s heads’ amongst quarrymen.
Macro images of White (above left) and Yellow (above right) Guiting Stone x50 magnification at the same scale. The circular white structures are ‘ooids’, the feature that defines this stone as a oolitic limestone. In the white stone the ooids are tightly packed and all more or less the same size, around 0.5 mm diameter. The Yellow stone has fewer ooids, of variable shape and size, alongside fragments of fossil shells.
The fossil scallop shell Propeamussium pumilum, found at the base of the Yellow Stone.
The Royal Oxford Hotel is built from Yellow Guiting Stone. This is the building that so alarmed William Arkell, he described the stone as ‘an offensive chrome yellow colour’.
The lower, clean face of the quarry (above left) is coated in ‘flowstone’, a sheet of crystals of the mineral calcite that has been deposited in cave-like fissures. A slot-like karstic fissure in the quarry floor (above, centre left). This miniature cave would have formed during the Jurassic when this layer was once exposed at the surface and began to dissolve away as rainwater and ground water penetrated the stone during a warm climate. Sawn blocks of oolitic limestone (above, centre right) with karstic weathering features infilled with calcite crystals. A tapered block of Yellow Guiting Stone – a ‘horse’s head’ (above right).
Ruth Siddall
References and Further Reading
Arkell, W. J., 1947, Oxford Stone, Faber & Faber, London, 185 pp.
Barron, A. J. M., Sumbler, M. G. & Morigi, A. N., 2002, Geology of the Moreton-in-Marsh district. Sheet description of the British Geological Survey, Sheet 217 (England and Wales). https://webapps.bgs.ac.uk/Memoirs/docs/B06081.html
British Geological Survey, 2000, Moreton-in-Marsh, England & Wales Sheet 217, Solid and Drift Geology, 1:50 000 Series, British Geological Survey, Keyworth, Nottingham.
Johnston Quarry Group, Guiting Quarry: https://johnstonquarries.co.uk/quarries/guiting-quarry/
Richardson, L., 1929, The country around Moreton in Marsh. Memoir of the Geological Survey of Great Britain, Sheet 217 (England and Wales).
Woodward, H. R., 1894, The Jurassic Rocks of Britain, Volume IV: The Lower Oolitic Rocks of England (Yorkshire Excepted), Memoirs of the Geological Survey of the United Kingdom, HMSO, London, 628 pp.