Westwood Ground Limestone
<NOTE: CONTENTS ARE BETA VERSION – SUBJECT TO FACT CHECK AND VERIFICATION>
The Westwood Ground Limestone is a type of limestone that is primarily found in the United Kingdom, specifically in the counties of Somerset, Wiltshire, and Gloucestershire. This limestone formation is a part of the Inferior Oolite Group of the Bathonian age, which is from the Middle Jurassic period, dating back to approximately 166-163 million years ago
Lithological Description
The Westwood Ground Limestone is a grey to cream-coloured limestone that is composed of fine-grained oolitic limestone, interspersed with shell fragments and calcite cement. It is a well-bedded and thinly laminated limestone, with layers of varying thicknesses that can range from a few centimetres to up to two metres. The limestone is highly porous and permeable and has a characteristic microcrystalline texture that is a result of the presence of ooliths
Thickness and Geographical Limits
The thickness of the Westwood Ground Limestone formation can vary significantly, with measurements ranging from 2 metres to up to 24 metres. It is present throughout the Cotswolds, and it stretches from the north of Bath in the east, to Stroud in the west. This limestone formation can be found across a range of hills, including the Cotswold Hills, the Clee Hills, and the Mendip Hills. It is also present in the Avon Gorge and the Bristol area (BGS, 2014).
Alternative Names
The Westwood Ground Limestone is also known by other names, such as the Chalfield Oolite, the Chalfield Stone, and the Ground Oolite.
Use of the Stone
An article in The Builder of 1895 (Anon., quoted in Perkins et al.1979) describes in some detail 47 working Bath Stone quarries in the Bath – Bradford-on-Avon – Corsham area. Of these, the higher, softer and purer level of the freestone (Bath Oolite) is still worked underground at Westwood (Westwood Ground), Limpley Stoke (Stoke Ground), Hartham Park at Corsham (see photo) and Monk’s Park and Elm Park to the south. The Bath Oolite here is up to 13 metres thick and there is enough shell debris and crystalline cement between the ooliths to make good building stone.
With the development of transport systems such as the Kennet and Avon canal and the Great Western Railway, its use spread further afield. It was even used in London by John Nash in the 19th Century (although it decayed so badly in the pollution that Portland Stone had to be used to replace it; the latter is particularly resistant to air pollution). The Westwood underground quarries were opened originally as a source of stone to build the railway, and it was the building of the Great Western Railway’s Box tunnel which revealed more valuable high quality stone running in the direction of Corsham, resulting in vast underground workings in this area below the Forest Marble Formation, which continue to the present day. By 1900 there was a network of tunnels and tramways for the removal of stone totalling around 60 miles in length.
Any irregularities or cracks ruin the stone for top-quality building, thereby reducing its value. The stone is soft and easy to work when first quarried. It is traditionally kept underground until May because the freshly quarried stone can be damaged by frost (owing to its high water content). It is then seasoned on the surface through the summer, when it loses water. The huge demand for stone in the 19th century resulted in unseasoned stone being used, with disastrous consequences. The stones must also be kept the right way up when building, with the bedding planes horizontal. Otherwise, fine layers will tend to flake off from the surface because weathering picks out any weaknesses in the bedding.
The Westwood Limestones and other Bath stones
Stone Name | Locality for past extraction of this stone (from Building Stones of England English Heritage – excel file) |
Westwood Ground | Wiltshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-west-wiltshire/); |
Bath oolite | Avon Buildings – Bristol, Bath (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-avon/); |
Bath stone | Avon Buildings – Bristol, Bath (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-avon/); Berkshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-berkshire/); Buckinghamshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-buckinghamshire/); Cambridgeshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-cambridgeshire/); Hampshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-hampshire/); Hertfordshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-hertfordshire/); Norfolk Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-norfolk/); Suffolk Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-suffolk/); Wiltshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-west-wiltshire/); |
Chalfield Oolite | Avon Buildings – Bristol, Bath (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-avon/); Gloucestershire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-gloucestershire/); |
Hartham Park Stone | Wiltshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-west-wiltshire/); |
Stoke Ground | Wiltshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-west-wiltshire/); |
Building using this stone (from Building Stones of England English Heritage – excel file) | |
Westwood Ground | Wiltshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-west-wiltshire/); |
Bath oolite | Avon Buildings – Bristol, Bath (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-avon/); |
Bath stone | Avon Buildings – Bristol, Bath (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-avon/); Berkshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-berkshire/); Buckinghamshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-buckinghamshire/); Cambridgeshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-cambridgeshire/); Hampshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-hampshire/); Hertfordshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-hertfordshire/); Norfolk Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-norfolk/); Suffolk Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-suffolk/); Wiltshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-west-wiltshire/); |
Chalfield Oolite | Avon Buildings – Bristol, Bath (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-avon/); Gloucestershire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-gloucestershire/); |
Hartham Park Stone | Wiltshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-west-wiltshire/); |
Stoke Ground | Wiltshire Buildings (https://historicengland.org.uk/content/docs/advice/building-stones-england/bse-excel-west-wiltshire/); |
Stone Name | Building Stones of England (English Heritage Regional Stone Atlases) |
Westwood Ground | Wiltshire stone (https://historicengland.org.uk/images-books/publications/building-stones-england-wiltshire/bse-wiltshire/); |
Bath stone | Avon (Bristol Bath) stones (https://historicengland.org.uk/images-books/publications/building-stones-england-bristol-bath-surrounding-areas/bse-bristol-bath-surrounding-areas/); Bedfordshire stones (https://historicengland.org.uk/images-books/publications/building-stones-england-bedfordshire/bse-bedfordshire/); Berkshire stones (https://historicengland.org.uk/images-books/publications/building-stones-england-berkshire/bse-berkshire/); Cambridgeshire stones (https://historicengland.org.uk/images-books/publications/building-stones-england-cambridgeshire/bse-cambridgeshire/); Essex stones (https://historicengland.org.uk/images-books/publications/building-stones-england-essex/bse-essex/); Hampshire stones (https://historicengland.org.uk/images-books/publications/building-stones-england-hampshire/bse-hampshire/); Hertfordshire stones (https://historicengland.org.uk/images-books/publications/building-stones-england-hertfordshire/bse-hertfordshire/); Merseyside stones (https://historicengland.org.uk/images-books/publications/building-stones-england-merseyside/bse-merseyside/); Norfolk stones (https://historicengland.org.uk/images-books/publications/building-stones-england-norfolk/bse-norfolk/); Somerset stones (https://historicengland.org.uk/images-books/publications/building-stones-england-somerset-exmoor/bse-somerset-exmoor/); Suffolk stones (https://historicengland.org.uk/images-books/publications/building-stones-england-suffolk/bse-suffolk/); Surrey stones (https://historicengland.org.uk/images-books/publications/building-stones-england-surrey/bse-surrey/); West Sussex stones (https://historicengland.org.uk/images-books/publications/building-stones-england-west-sussex/bse-west-sussex/); Wiltshire stone (https://historicengland.org.uk/images-books/publications/building-stones-england-wiltshire/bse-wiltshire/); |
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References:
<stone name> | |
Reference | B2 |
NAME | Westwood Ground |
TYPE | Limestone |
GEOLOGY | Jurassic. Great Oolite |
COUNTY | Wiltshire |
COLOUR | Cream |
TEXTURE | Medium grained oolite |
BLOCK SIZE LXBXH (mm) | 750-1200mm depth on bed |
SUITABILITY | Ashlar, dressings and weathering courses |
USES (1) | All Saints Church, Fulham, London |
USES (2) | Barnards Inn, Fetter Lane, London |
USES (3) | British Petroleum HQ, Hemel Hempstead |
USES (4) | |
Stone Names | Bath stone |