The Museum of Bath Stone Story

Around 160 million years ago, the land the became Combe Down was under a warm, shallow, tropical sea. Tiny fragments in this warm sea became coated with thin layers of calcium carbonate, forming egg-shaped stones known as ‘ooliths’. Over time they became compressed to form oolitic limestone – the stone that built Bath.

The honey-coloured limestone became known as Bath Stone and subsequently, gave that name to the era in which it was formed. The Bathonian is an age of the Middle Jurassic. It lasted from approximately 168.3 to 166.1 million years ago.

Combe Down lies on a plateau capped by Great Oolite limestone; a high-grade limestone known as a freestone – one that can be worked from any face (unlike slate etc.) It is very soft when first quarried and can be easily worked.

Stone-age man may have used it; in the Roman and Medieval periods, Bath Stone was extensively used. However, it was the Georgians and the partnership of John Wood, the Edler, and Ralph Allen who made it a household name.

In 1725, John Wood sent a plan to develop Bath into a grand Palladian city to Ralph Allen. Ralph Allen acquired all the quarries on Combe Down, mechanised the whole operation, including shipment, and the building of Bath Began.

Ralph Allen died in June 1764, 71 years old. As he had no heirs, the business went to his niece, Mary Allen. The estate had large debts, so equipment was sold, and the quarries were leased to multiple tenants. Among the tenants was Philip Nowell, whose legacy included the building of major extensions to Longleat, Windsor Castle and Apsley House. In 1788, Allen’s estate passed to Earl De Montalt, widower of Allen’s niece. About 40 years after Allen’s death, the land he had accumulated on Combe Down was sold off by his heirs to pay off the debts that the 1st Viscount Hawarden had accumulated. By the 1820’s, many of the underground quarries had been abandoned.

The discovery of large deposits of Bath Stone in the Corsham area, during the construction of Box Tunnel for Brunel’s Great Western Railway in 1841, hastened the decline. The new stone was not as good, but it was easier to mine and ship and, therefore cheaper.

Combe Down Stone was still sought after, and some of the small quarry operators continued to produce it to the end of the 19th Century. It was exported as far afield as Cape Town, where it was used to build the City Hall in 1905.

The stone was mined by the room and pillar method where caverns were dug out leaving huge pillars holding up the roof. Local entrepreneurs continued to chip away at faces and pillars without worrying too much about where they were working in relation to other owners or how fat the pillars should be.

Bats and, small children with string and candles in a jam-jar, became frequent users of the abandoned mines.


The Problem

In the late 1980s, a utilities contractor dug through into the mine when digging a trench. In 1987, a gale blew over 6 of the Seven Oaks at Rainbow Wood, as well as the self-seeded chestnut tree in Firs Field, which exposed a gaping hole into the mines. Word got around about the honeycomb under Combe Down and, houses became difficult to insure and mortgage. It became difficult to sell or buy a house locally.

Surveys were carried out; parliament became involved and, funding was sought. An estimated 82% of the stone under the village had been removed and in places, the remaining roof was down to 2m thick. There was a real possibility that Combe Down could one day disappear in a cloud of stone dust.

A fight began around the best aggregate to be used. A cheap option was Pulverised Fuel Ash – PVA; a waste product from a nearby power plant in Wales. This was found to be uneconomic once the poisonous elements in the material had been neutralised and, prevented from entering the water courses.

Foamed concrete was deemed the best material and was ably poured over 10 years to 2010 by newly redundant Welsh miners.

A condition of the funding, which came largely from the Homes and Communities Agency, was that a visitor’s centre be maintained to safeguard the heritage and artefacts, to educate the public and to be available for the use of the local community.

The Ralph Allen CornerStone opened on July 19, 2014. It has recently been renamed the Museum of Bath Stone and continues to tell the story of Combe Down, its stone and its people.