Development of Sustainable Georesources for the Built Environment in the United Kingdom

. The character of the UK’s built heritage has been largely determined by the country’s diverse geology. Indigenous natural stone forms a major component of the nation's pre-1919 building stock. Stone has been used traditionally for roofing, roads, pavements and bridges and engineering works and all forms of walling. Today it is mostly employed as thin panel cladding to concrete frameworks in modern construction and is now increasingly being used in large volumes for new city streetscapes. This paper outlines the material requirements for the repair and maintenance of the stone-built heritage and illustrates a range of initiatives across the UK aimed at safeguarding and redeveloping indigenous resources. The importance, particularly for the repair and conservation sector, of selecting appropriate replacement stone is being recognised by architectural and conservation professionals and by local authority officials. There is also increasing recognition of the importance to the economy of the local character of the built environment in terms of its value to tourism and to architectural, historical and cultural identity. The paper also examines the historical sources of information on stone in the UK and offers recommendations for databasing and disseminating stone resource information. This may assist the redevelopment of a healthy indigenous stone industry and ensure that the unique built heritage character of the UK is maintained and enhanced.


INTRODUCTION
During the mid-to late-1800s the UK had several thousand working building stone quarries and mines in sandstone, limestone, igneous and metamorphic rocks that supplied local and national requirements. Quarries ranged in scale from those supplying material for individual buildings (e.g. farmsteads) to the needs of villages, towns and cities. As their reputation for producing good quality stone increased, quarries of national importance developed export markets for masonry stone, pavement and setts to Europe and North America. In the early part of the 20 th century the decline of the building stone industry coincided with the manufacture and utilisation of other building materials, most notably concrete. In 2005 there were approximately 440 working quarries in the UK supplying exclusively building and pavement stone. In some cases, specific rock types are no longer quarried. In Scotland, for example, new supplies of indigenous slate, principally for roofing, have not been available since the 1950s, and there are currently less than 20 quarries supplying sandstone, one of the most important building materials in northern Britain.

NATIONAL INITIATIVES TO IDENTIFY AND SAFEGUARD INDIGENOUS RESOURCES
The safeguarding of resources for future use is a crucial element of the sourcing of indigenous stone. The UK Government's response to the Rio Earth Summit on Sustainable Development (1992) noted that '.... it will become increasingly important to have reliable information about the nature, quantity and location of mineral resources as workable reserves in environmentally acceptable areas become scarcer.'… Legislative planning for minerals working varies from country to country in the UK but Government minerals planning policies now make specific reference to the identification and safeguarding of building stone resources (Department for Communities and Local Government 2006;Scottish Executive 2006).

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The development and use of locally sourced sustainable natural stone for the built environment is an important consideration for the construction industry. Today's global market has encouraged the importation of stone for new-build cladding and for new city streetscapes.
Whilst this may positively influence public acceptance of the use of natural stone, consideration needs to be given to the use of 'like for like' indigenous materials for repairs and conservation work and the use of indigenous stone for some new build developments. This should ensure that the unique local character of buildings and urban environments is not lost for future generations.
The importation of stone, produced more cheaply in less regulated environments overseas, greatly exceeds UK exports of this commodity (Figure 1). There is nevertheless an urgent need to examine the many benefits of using a higher proportion of local resources that may reduce transport and processing energy requirements and, in turn, reduce the related carbon footprint of the industry. Geological Survey (BGS) is developing a geodatabase of former quarry sources, accessed via a Geographical Information System to assist decision-making for repair and maintenance, the selection of stone for both conservation and new build, and planning for the reopening of former quarries. In addition the BGS provides petrographical advice on the selection of appropriate replacement stone for specific building repair projects throughout the UK.

England and Wales
Initiatives in Wales and England also reflect a growing awareness of the importance of

GEODIVERSITY AND ITS INFLUENCE ON THE BUILT HERITAGE
The UK's geological heritage dates back to some 3.1 Ga. A wide range of sedimentary, igneous and metamorphic rocks have been used for building purposes. Processes during the last 2.6 Ma (Quaternary) have redistributed surface materials and scoured the landscape providing ready sources of sands, gravels and clays for building purposes. This rich geodiversity has led to the use of many different building materials and as a result stone forms a major component of the pre-1919 building stock. Stone has been used for masonry, roofing, streets, pavements and bridges and all forms of walling, and is today being used in large volumes for new city and town streetscapes.        Carboniferous sandstone from this working was recognised by architects in the early 19th century as a suitable alternative to Craigleith Sandstone (see above), and modern analysis confirms the petrographical similarity of the two sandstones (Hyslop & McMillan 2004).
Sometimes, planning restrictions may constrain a quarry or a new excavation adjacent to old workings to be opened only for a short duration to supply material for specific building projects.
An example of this practice (known as 'snatch' quarrying) was at Binny, West Lothian, west of Edinburgh, in the 1990s to supply material for specifically to repair the Walter Scott Monument in the city.

SOURCING INFORMATION ON STONE RESOURCES
Over the past three centuries with the rapid increase in use of mineral resources to feed firstly the development of the industrial revolution followed by subsequent economic prosperity, the requirement to locate, understand and quantify mineral resources became essential. In 1835 the quest for such knowledge was identified as a key factor in the establishment of the Geological MAEGS15 Conference -paper for Estonian Journal of Earth Sciences 9 As huge numbers of quarries were abandoned during the 20th century some were re-used as sources of hard rock aggregate. However many were abandoned, later to be infilled in a variety of ways (e.g. with colliery spoil, domestic refuse and other landfill schemes), and, particularly in urban settings, some became sites for new housing or retail development. Other quarries lie dormant, either water-filled or open vegetated holes. Some have significant biodiversity and/or geodiversity interest, and others in recent years have been recognised for their recreational potential (e.g. rock climbing).

Regional publications
From the 1980s onwards geologists working in the UK have recognised the value of documenting known sources of stone and linking those sources to the stone built heritage. Early studies (see Robinson, 1984-and subsequent volumes for London -and Bennett, 1996 showed the concept of geodiversity and the links between natural and built heritage could be developed. In Scotland initiatives such as those for Glasgow (Lawson 1981) and for Edinburgh (Bunyan et al. 1987;McMillan et al. 1999) have stimulated much interest beyond the geological fraternity.  , published by UNESCO Publishing in association with the International Association of Engineering Geology, Historic Scotland and the British Geological Survey. This book provides an index to the principal sources and uses of stone. The next stage of research is to develop in depth regional volumes, from which it may be possible to identify key resources worthy of detailed modern resource assessment.

MODERN RESOURCE ASSESSMENTS
Sourcing of indigenous stone is vital particularly as conservationists and architects are increasingly conscious of the need to use natural stone appropriately both for repair and for new building. Recent publications have aided the initial evaluation of the resource process, for example the first Building Stone Resources Map of Britain (British Geological Survey 2001). This map, underpinned by databases, outlines the principal sources of stone and links them to geological formation and lithology. Such data when used with other sources (e.g. BGS resource publications, archival data) are valuable aids for a range of building stone enquiries.
The BGS is developing its UK-wide database BRITPITS to assist in accessing information on quarry sources, products and geology. BRITPITs contains over 2400 entries covering active mineral workings in the UK of which a small proportion are currently producing building stone, together with approximately 15000 entries for inactive and former sites. It forms the basis for the Directory of Mines and Quarries published regularly by the BGS (Cameron et al. 2005).
Summary data are available for a range of minerals, including building stone, via a Minerals-GIS Online Service for the regions of England and Wales (see www.mineralsuk.com).
BRITPITS is also being used to store information on sources of stone used in buildings.

Quarries information together with geological map data may be reviewed in a Geographical
Information System (GIS) (Figure 8). These databases used together with the BGS's extensive rock and thin section collections aids the identification of original stone sources and appropriate replacement stone for building repair from currently active quarries. The need to meet international and government sustainability targets has encouraged a fresh examination of the benefits of using local resources, for example by a reduction in transport and processing energy requirements. There is a steadily increasing recognition that natural stone is not only aesthetically more pleasing and durable but also compares favourably with other building materials in terms of life cycle cost analysis (Historic Scotland 1997;Natural Stone Institute 2005).
Provision of accessible information on stone is a pre-requisite for informed decision-making to maintain and enhance the UK's built heritage. Fullest utilisation of information sources should be made to enable strategic planning of building stone resources. This involves thorough archival and literature research coupled with field assessment.
Dissemination of resource information via regional publications and an online service such as www.mineralsuk.com may provide ready access for those requiring information, such as architectural practices, local and central government. The applicability of methods employed by the Strategic Stone Research initiatives being developed by English Heritage for England and a new Natural Stone Database for Northern Ireland, shortly to be launched, should be assessed. In this way, the necessary information can be accessed to conserve and sustain the UK's stone built heritage for future generations.