Oxfordshire's origins are cast in stone

The diversity of the building materials is being revealed by the results of a pioneering survey by volunteers of more than 100 of our communities.

This survey, the Oxfordshire Strategic Stone Study, is due to be finished by the end of May and is being carried out by members of Oxfordshire Geology Trust (OGT).

While members of OGT have been concentrating on the county, the survey is part of a regional pilot scheme initiated and supported by English Heritage.

Bill Horsfield, OGT treasurer and a retired geologist, said: “English Heritage and the British Geology Survey wanted to find out the main types of building stones, where materials came from and the locations of existing and former quarries. The information would be valuable to assist in the restoration of buildings with the same original materials or matching stone. It would also be of use to planning authorities who give guidance on proposed new buildings.”

Locating old and existing quarries can also help in specific renovation work.

When the National Trust wanted to carry out extensive restoration to Ashdown House in the Lambourn Downs in 2005 it was able to reopen a chalk quarry at nearby Compton Beauchamp to provide new blocks of the hard chalk known as Melbourn Rock that was used when the mansion was originally built.

To organise its long-term survey, English Heritage initially approached individual geology trusts in eight counties in the south-west Midlands all of whom had experience of working together.

Oxfordshire was one of the group and the others were Herefordshire, Worcestershire, Gloucestershire, Shropshire, Warwickshire, Wiltshire and Bedfordshire.

The pilot scheme will eventually be rolled out across the country with other groups of geology trusts.

“In Oxfordshire we already had been involved in something similar since 2007 as we worked with geology trusts in Berkshire and Wiltshire on a project sponsored by the North Wessex Downs Area of Outstanding Natural Beauty,” said Bill.

The northern boundary of the AONB is roughly on the line of the ancient Ridgeway, passing south of Wantage and south of Harwell and Didcot.

This study resulted in the publication of a brochure exploring the links between building materials and styles and the local geology in the AONB.

For the English Heritage survey a small group of OGT members have been touring the county and have mapped out 15 different building stones, including Chipping Norton limestone, Taynton limestone, White limestone and Marlstone, which is the orange-coloured ironstone found in villages around Banbury such as Deddington, Bloxham, Adderbury, Great Tew, Hornton, Wroxton and Hook Norton.

It was also used for Broughton Castle and Chastleton House. Marlestone was also used in decorative work at the University Museum (1859) and the Christ Church Meadow Buildings (1862) in Oxford.

“Although many of the stone types look superficially similar, it is possible to recognise differences in the colour, texture, fossil content and the hardness of stones in most villages, particularly where a stone type is dominant and the distribution of most types of stone is not difficult to map out,” said Bill.

Burford, for example, is easy to identify as it was mainy built out of Taynton limestone.

As expected, Chipping Norton limestone was used extensively in the town and neighbouring villages, and the materials came from a nearby quarry and another at Charlbury.

“It has been fascinating to find out how — with few exceptions — builders used local stone that outcropped and could be quarried within a few miles of where it was to be used. Stone used in villages and towns was available locally,” said Bill.

An example are the early Oxford colleges that were constructed of limestone from quarries in Headington and Wheatley, although later it was considered worthwile bringing in the better quality Tayton limestone, which was used across Oxfordshire for high-status buildings.

Some stone is available in a restricted area and one of these is Forest marble — a coarse-grained shelly limestone — which was quarried from the Wychwood forest region around quarries in Filkins and North Leigh.

It was used for cottages and a village centre at Filkins and further afield for the Morris Memorial Cottages at Kelmscott.

One of the most familiar materials is Stonesfield slate, a flaggy type of sandstone found only in Stonesfield village. It was used for roofing tiles across the Cotswolds.

In south Oxfordshire, the available geological materials have generally made poor building stones.

A creamy-grey material called chalk clunch was used but has weathered poorly for some years. It can be found in buildings in the Blewbury, Wallingford and Benson area.

Flint is another material found in the southern region and, though it is difficult to handle, it can be cut or knapped into shape and has been incorporated into brick and limestone walls. A prime example is the chequerwork at Ewelme church.

Among the books that gave OGT members guidance was Oxford Stone by W J (William) Arkell that was published in 1947 with a reprint in 1970.

Arkell was a member of the Swindon brewing family and was a university geologist based in Oxford.

“He was writing at a time when there were many quarries still active and he was able to incorporate the local knowledge of quarrymen. There are now only a handful of active building stone quarries left in Oxfordshire,” said Bill.

Originally, OGT was the Oxfordshire RIGS group, named after the then 40 designated regionally important geological sites.

It became Oxfordshire Geology Trust in 2003 and has a programme of conserving old quarry outcrops and educational outreach activities and published a series of brochures under the title of Secrets in the Landscape.