The illegal trade in layers of history

Another Life: The heft of a slab of limestone is like that of no other rock. Your hands expect something, if not exactly light to lift, then at least appropriate to the smooth and silvery image in your mind.

Instead, there is this sudden, dead-weight drag at the fingers, like a bucketful of wet sand or sea water. What you are hoisting is the essence of ocean past, the skeletal debris of seabed life ground down into limy mud over, perhaps, 30 millenniums, 300 million years ago. The slab grates and clunks as you ease it back gratefully into place on a wall you really had not meant to knock.

"Do not lean against the wall when examining it," counsels naturalist Gordon D'Arcy in his new book The Burren Wall (Tír Eolas, €12).

And if he neglects to mention the special shock of limestone in the fist, as it were, he is sensitive to the special effects it makes possible - in particular those magical, fretted walls built of individual stone fragments, in which weight and friction join to cheat the gusts from the Atlantic.

"One is left with a strange thought," he writes. "The drystone wall is not so much a case of stone on stone as stone on space: chunks of stone, chips of light." Close up, "the hand is drawn to the sun-warmed surface, the fossiliferous texture, to the fretted surface and the bedding planes". Further off, the eye stops looking for "peekaboo" holes and "sweeps sideways, noting pattern - stacked, herringbone, layered, eclectic". At a distance, picked out by winter sunshine, the walls become a golden embroidery, stitching the shapes of enclosures on the grey mantle of the landscape. Aesthetically and culturally, they have been overdue for a documentary celebration. D'Arcy's slim but elegant book explores their social history, the successive styles of construction, and also the natural history that inspires his sunny watercolours.

The Burren walls are unique as vertical habitats, the fossils locked in their stones linking today's living wildlife with a patterned gallery of corals, shellfish and trilobites from another lost world. Hung with lichens, mosses and ferns, the walls are a skyway for stoats, a song-perch for cuckoos (six calling at once on a summer morning are still "not unusual", says D'Arcy), a labyrinth for lizards and a storehouse for field mice, who hide caches of hazelnuts between stones at the base. One envies the children around the Burren, who, thanks to the efforts of D'Arcy and others, are making all these wild secrets a vivid pleasure of their school days.

Most of the walls now seem safe enough within the 28,000 hectares of the Burren protected by Special Areas of Conservation. But what of limestone pavement, that sculptured, flower-hugging fabric of karst country so coveted by the cheque-book gardener? In the decade or so since the UK protected its own limestone uplands, there have been persistent reports of a substitute supply from Ireland.

All damage to the pavement in an SAC is illegal under EU habitats regulations and more than 40 limestone pavement sites have been secured, most of them in counties Clare, Galway and Mayo. In 1997, Mayo County Council refused planning permission for the quarrying of pavement at a site near the shore of Lough Mask, and in 1999 a Co Clare man was sentenced to four months in jail for removing up to 90 lorry-loads - a rare but salutary prosecution.

At that time, an investigation funded by the UK's Countryside Agency and our Heritage Council found at least 13 Irish traders involved in extraction of water-worn pavement. They were shipping out 9,000 tonnes a year to UK stone merchants supplying landscape designers, garden centres and DIY stores. Since then, the Wildlife Act has set fines of up to €70,000, and up to two years in jail for causing damage to pavement in either SACs or Natural Heritage Areas.

The trade continues, however - most probably from unprotected areas and unconsidered corners where development is biting into limestone outcrops.

Earlier this year, a further report was published, from research undertaken by the Countryside Agency on behalf of the UK's Limestone Pavement Biodiversity Habitat Action Plan working group (gosh!). The report, Shattered Stone, found Ireland still contributing an unspecified share of some 8,000 tonnes of water-worn limestone a year, most of it selling at £120 (€175) a tonne.

The buyers are keen gardeners and landscape designers, mostly in the affluent and trend-setting southern counties of England. They are inspired, says the report, by the makeover gardening programmes on TV and are prepared to pay £120 a tonne for slabs and chunks of immemorial, rain-polished rock.

May they drop it on their toes.