11 MAY 05

I'm standing in the rain on a steep fell in Cumbria, watching the clouds curl round the cliffs high above me. A scree spills down the hillside: a cascade of boulders bursting through the soft green earth. Sky, rock and land are united in the distinctive grey-green tones of the Lake District. The scene ought to be elemental, but the fleeting sight of a large earth-mover high up on the fell-side suggests that all is not what it seems.

I am in fact climbing the approach to the quarry on the Kirkstone Pass, a guest of the manager, Nick Fecitt. I'm here to check out the environmental credentials of one of the key materials in the palette of Tree House: Kirkstone slate. We are off to a good start, for the hillside is actually a restoration, an old quarry scar filled with stone waste then carefully seeded to recreate the appearance of the surrounding fells. Given the location of the quarry in the middle of a national park, this work is essential to sustaining a long-established industry in an area where tourism now has first priority.

Kirkstone slate is principally used for high quality floor and wall tiles and for work surfaces. The 'Silver Green' slate is the most distinctive in the range as every tile is patterned with fine bands of grey and green, seemingly cut against the grain of the rock. At the top of the quarry, where huge boulders are being dragged out of the mountainside and split by the earth-movers, Nick explains their origin. The stone was formed by a series of volcanic eruptions, each of which created a new layer of mineral and ash deposits. Then, in the collision of the islands that preceded Scotland and England, this rock was thrust upwards and compressed against the grain of the original sedimentation. Consequently, the rock now cleaves at right angles to the volcanic layers, exposing the early geological history of the rock on every tile.

The timeless beauty and strength of slate are its core eco credentials. Like wood, most stone has an appeal that suffers little from the vagaries of fashion and so typically enjoys a long life once installed. This is only possible because it is so hard-wearing and durable; even if your floor does get ripped up by future inhabitants with dubious taste, the stone will hopefully achieve a long life via the reclamation yards.

Nick shows me the progression of the slate from cliff-face to consumer product, a journey through a series of bleak sheds where huge circular saws cut and hone the rock, first into blocks and then into tiles or larger slabs for work surfaces. Although the transformation is remarkable, I am struck by how simple the process is, requiring relatively little energy and no toxic extras. This is a major environmental advantage of stone: the tough part of the manufacturing process has already been done by Mother Earth. Unlike concrete, bricks, ceramic tiles and synthetic finishes, no further firing is needed beyond that completed several million years ago.

As we drive back to the company office in the valley below the pass, Nick draws my attention to the local buildings. Although slate still defines the character of the Lake District, its ubiquitous use in earlier buildings is not matched in many more recent constructions where rendered block walls and concrete roof tiles are also in evidence. The UK building industry has long departed its local roots, to the extent that using British (let alone local) stone is exceptional. Unfortunately the eco-profile of stone droops dramatically as soon as you start importing it, given the energy required to transport it. South London may not be Windermere but a truck on the M6 is a relatively small eco-cost to pay compared to ships from the south seas.

Kirkstone isn't cheap but it is gorgeous: I am confident that its unique character will pay long term dividends. If you’re in the market for a high quality durable finish, think twice before you shell out for Indian sandstone or Italian travertine and consider buying a slice of an English national park instead.

For a Kirkstone catalogue, phone 01539 433296 or see www.kirkstone.com.