The individual marble beds (also known as 'seams'), lie between layers of softer marine clays and mudstone, laid down during repeated marine ingressions. Some of the beds contain iron oxide/hydroxide minerals, such as hematite or limonite, giving red or brown varieties, while other beds contain glauconite giving a green (or occasionally blue) colour.[3]
Occurrence
Purbeck Marble is found at outcrop, or beneath superficial cover, all the way across the Isle of Purbeck from Worbarrow Tout in the west to Peveril Point in the east. The marble beds are never more than 1.2 m thick and are often much thinner. The outcrops lie within the Purbeck Monocline, with the beds dipping moderately steeply to the north.[4]
It has been less used in modern times, but a remarkable example is the church at Kingston, Purbeck, Dorset built in 1874–1880.[8]
Other strata of Purbeck Limestone are being quarried at the present time (2021). Purbeck Marble was previously extracted in 1993.[9]
Purbeck Marble is used by a number of contemporary sculptors, such as Emily Young.[10]
Interlaced semicircular arches supported by Purbeck Marble shafts in the Temple Church, London
The 13th-century south transept of Beverley Minster, richly decorated with Purbeck Marble shafts.
References
^Arkell, W. J. (1947), Geology of the country round Weymouth, Swanage, Corfe Castle and Lulworth. London: HMSO for British Geological Survey.
^Clements, R. G. (1993), "Type-section of the Purbeck Limestone Group, Durlston Bay, Swanage, Dorset", Proceedings of the Dorset Natural History and Archaeological Society, 114, 181–206.
^Beavis, John (1971), "Some aspects of the use of Purbeck Marble in Roman Britain", Proceedings of the Dorset Natural History and Archaeological Society, 92, 181–204.
^Leach, Rosemary (1978), An investigation into the use of Purbeck marble in medieval England, 2nd edition. Crediton: the author.