Combe Down Limestone

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Geological Formation of Combe Down Limestone

Combe Down Limestone is a white to cream-coloured limestone that was formed during the Jurassic period, between 201 and 145 million years ago. The stone was formed in a shallow marine environment, from the accumulation of biogenic and clastic sediments.

Lithological Description and Thickness

Combe Down Limestone is a bioclastic limestone, composed mainly of fragments of crinoids, foraminifera, bivalves, and corals, with minor amounts of quartz and feldspar. The stone has a fine to medium-grained texture, with a porosity ranging from 3% to 18%, and a density of around 2.5 g/cm3.

The Combe Down Limestone is up to 27 meters thick and is separated into two beds: the Combe Down Base Bed and the Combe Down Top Bed. The Base Bed is 6-10 meters thick, whereas the Top Bed is 15-18 meters thick. Both beds have similar characteristics, although the Base Bed tends to be slightly finer-grained and more homogeneous.

Geographical Limits and Alternative Names

Combe Down Limestone is quarried from the Combe Down and Bathampton Down mines, located near the city of Bath in Somerset, England. The stone is also known as Bath Stone, as it has been quarried in the area for over 2,000 years and has been widely used in Bath’s historic buildings. Other alternative names for the stone include Bath Oolite, Bath Freestone, and Bath Stone Oolite.

Use of Combe Down Limestone

Combe Down Limestone has been widely used in construction, extensively quarried in the Combe Down area of Bath, England and particularly used in the historic buildings of Bath. The stone’s fine texture, light colour, and workability make it an attractive and versatile building material

1. Bath Abbey, Bath, England: Bath Abbey is one of the most famous buildings in Bath and is known for its striking gothic architecture. Combe Down limestone was used in the construction of the abbey’s exterior walls, which were built between the 1490s and the early 16th century. (Reference: “Bath Abbey,” Bath Preservation Trust, accessed February 23, 2023, https://www.bath-preservation-trust.org.uk/bath-abbey/)
2. The Circus, Bath, England: The Circus is a historic street in Bath that features a circular layout with three segments of townhouses. The street was designed by architect John Wood the Elder and was built between 1754 and 1768. Combe Down limestone was used in the construction of the street’s exterior walls and facades. (Reference: “The Circus,” National Trust, accessed February 23, 2023, https://visitbath.co.uk/things-to-do/the-circus-p56201
3. Pulteney Bridge, Bath, England: Pulteney Bridge is a historic bridge in Bath that spans the River Avon. It was designed by architect Robert Adam and completed in 1774. Combe Down limestone was used in the construction of the bridge’s exterior walls and parapets. (Reference: “Pulteney Bridge,” Visit Bath, accessed February 23, 2023, https://visitbath.co.uk/things-to-do/pulteney-bridge-p56151)
4. Beckford’s Tower, Bath, England: Beckford’s Tower is a historic tower in Bath that was built for writer and collector William Beckford in 1827. The tower features a spiral staircase and offers stunning views of the surrounding countryside. Combe Down limestone was used in the construction of the tower’s exterior walls. (Reference: “Beckford’s Tower,” Bath Preservation Trust, accessed February 23, 2023, https://beckfordstower.org.uk/)
5. The Royal Crescent, Bath, England: The Royal Crescent is a famous row of terraced houses in Bath that was designed by architect John Wood the Younger and built between 1767 and 1775. Combe Down limestone was used in the construction of the crescent’s exterior walls and facades. (Reference: “The Royal Crescent,” National Trust, accessed February 23, 2023, https://visitbath.co.uk/things-to-do/the-royal-crescent-p56191)

In addition to the use in grand buildings, Combe Down Limestone has been used in many smaller-scale projects, including houses, churches, and public buildings. For example, the village of Biddestone in Wiltshire is noted for its picturesque cottages built from Combe Down Limestone.

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Further reading

https://en.wikipedia.org/wiki/Combe_Down

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