Travel Fossils: Cornwall's man-made alps

The China clay industry has left its mark on the Hensbarrow Downs.

THE WHITE Pyramid sounds as if it should be the finest of all the ancient Egyptian sites, or at the very least the glitziest new ride at Alton Towers. In fact, it is a pub in the Cornish village of Trewoon. And if you arrive after dusk, and enquire why it should have so strange a name, the locals may regard you with the look they reserve for the most glaring emmet (tourist). But at sunrise, all becomes clear. The hillside behind the pub is dragged upwards in a neat ice-cream white cone. This mountain is no gigantic Cornish vanilla, though: it is the by-product of the China clay workings.

The economic history of Cornwall is more complicated than tourism replacing tin as the main source of income. A glance at the Ordnance Survey map reveals an expanse of white blotches that look like a particularly nasty skin complaint. But when you exchange the blank two dimensions for the real three, the Cornish Alps acquire a strange beauty.

Man has imposed his own geometry upon the Hensbarrow Downs. The artificial mountains are best seen from the curious branch line that meanders from the north coast to the south. The peaks are mostly ghostly grey, as if all the snow that has ever fallen in Cornwall has been piled up in slushy heaps. The actual main ingredient is quartz, washed from the clay that binds it. For each ton of clay produced, five tons of waste results. Given that 1 million tons of fine clay are produced each year, you can see how the White Pyramid was briskly created.

The corresponding valleys are pits a mile or more across. Workers have dug deep into the layer of decomposing granite that water has turned into clay. Not any old clay: the only other place you find clay of this quality is in northern China.

A chemist from across the border in Devon, William Cookworthy, hit upon the purity of Cornish clay in 1755. Despite mechanisation, the basic method remains the same: bombard the stony porridge with water, and repeat as necessary until the clay is freed. The next problem was about how to export it. The clay was dragged downhill to Charlestown, a fine old harbour which looks so picture-postcard perfect that it should be a film set (which, indeed, it frequently is). Stout sea defences protect the port, around which sturdy granite warehouses and offices are still scattered, even though most of the clay now departs by rail. So the dirty, dusty business of trade no longer interferes much with the more picturesque industry of exploiting the Cornish coast. But above the boisterous waters of St Austell's Bay, you can just make out the gaunt shadow of the White Pyramid.