For a geologist, waterworn limestone pavement is the surface skin of karst, the fissured landscape of places such as the Burren. For an ecologist, it is a rare and precious habitat, cradling special flowers and ferns in its crevices and hollows. For anyone who loves nature or art or the history of Earth, the pavement is compellingly strange and beautiful: Tim Robinson's "uniquely tender and memorious ground".
Despite the Irish boom in gardening, the fancy to buy a load of water-worn limestone and build a rockery has not yet taken hold. But for many of Britain's better-off gardeners, such stone is just the job for an authentic rockery, even at a retail price of £160 sterling a tonne. More modest back gardens may do with artful clusters of handsized chunks, chosen from a garden-centre bin at £3 to £4 a piece. Big or small, most of the stone now comes in lorries from Ireland, wrongly promoted by the trade as a "sustainable" source.
The UK has comparatively little limestone pavement of its own - less than 3,000 hectares - notably in Cumbria, Lancashire and Yorkshire - and very little of it remains intact. The most important areas have been listed as Special Areas of Conservation (SACs) under the EU Habitats' Directive, and special Limestone Pavement Orders have helped to choke off the burgeoning trade in stone for rockeries and landscaping. As the last legal slabs are skinned from a traditional quarry in Westmorland in north-west England, the Republic is left as the main supplier, not only for the UK but for a growing demand on the European mainland. An investigation by Traffic International, funded jointly by the UK's Countryside Agency and Ireland's Heritage Council, found at least 13 Irish traders involved in extraction and export, and water-worn limestone being excavated from 10 key sites.
The report, published last year, questioned the legality of some of the operations at that time. Between them, in 1999, they were supplying around 9,000 tonnes a year to the UK importers, much of it travelling by lorry on the Larne-Stranraer ferry route.
The Republic has so far selected 42 limestone pavement sites for protection as SACs, most of them in counties Clare, Galway and Mayo. This includes three separate SACs, totalling 28,500 hectares, in the Burren. All damage to the pavement in an SAC is illegal under the EU Habitats Regulations, and in 1999 a Co Clare man was sentenced to four months imprisonment for removing up to 90 lorry-loads of stone.
One of the photographs in the Traffic report, On Stony Ground, shows a digger wrenching up deep slabs of pavement "near the Burren". Here, at the margins of the Burren National Park, great stretches of open pavement and limestone scrub have already been cleared or "reclaimed" and spread with imported topsoil to create ryegrass cattle pastures.
Another photograph is of a rock-drill at work at a big extraction site "in Co Mayo". In 1997, An Bord Pleanala confirmed the refusal of Mayo County Council to allow the quarrying of pavement at a site near the shore of Lough Mask. This was in a Natural Heritage Area (from which SACs are selected) and the prime objector to planning permission was the National Parks and Wildlife Service of Duchas. In the new Wildlife Act, fines of up to £50,000 and imprisonment of up to two years will protect pavements in both SACs and NHAs - formidable penalties if seriously enforced.
Outside of protected areas, however, planning permission is not needed for operations below 2.5 hectares - still a good-sized patch of pavement. This watersculpted rock took thousands of years to form, supports some very special plant communities, and is in no real sense renewable. Despite the sales-line of some UK stone suppliers, the piecemeal destruction of our unprotected pavements is certainly not a "sustainable alternative" to Westmorland stone, long the prized substance of rockeries in Britain's great gardens.
The Traffic International report commented on a telling difference in attitude between Irish people involved in limestone extraction and those in the trade in England. "All extractors contacted in the Republic of Ireland commented that despite having been approached by the authorities enforcing the SACs, they would all continue to extract water-worn limestone to meet the demand." By contrast, many UK quarries and garden centres would not stock what could be illegal material, or simply did not condone the trade. The new penalties of the Wildlife Act should command rather more respect.
Traffic International, a joint programme of the World Wide Fund for Nature and the World Conservation Union, is based in Cambridge and took its research brief from the UK's Limestone Pavement Biodiversity Action Plan Working Group. Dr Liam Lysaght, ecologist with the Heritage Council, sits in on the group, which is trying to find new avenues of conservation. Enforcing the law and educating gardeners out of their dreams (or wooing them with plausible imitation stone) seem to be the best available options.
Meanwhile, a most informative, well-illustrated guide to Ireland's limestone world is The Karst of Ireland: Limestone Landscapes, Caves and Ground- water Drainage Systems, a booklet published by the Working Group on Karst and on its way to schools and libraries. It draws on a wide range of experts in universities, the Geological Survey of Ireland and other professionals involved with the water-laced platform of rock that lies under half of Ireland.
Being geologists, they are keen to promote a better knowledge of karst at this frenetic juncture in Irish development. Tunnels, drains, mines, reservoirs, motorways, building foundations, are all likely to invade its unpredictable cracks and cavities. The rock is the source of most of our largest springs, and its deep reservoirs of groundwater need special protection from pollution.
Some copies of the karst booklet are available free from the Working Groups secretary, Donal Daly, at the Geological Survey of Ireland, Beggars Bush, Haddington Road, Dublin 4. E-mail: donaldaly@gsi.ie.
