A Horse Path

Chalk

COMMONPLACE stuff at first glance, but chalk is special. In no other part of the geological record are the connections between landscape, flora, farming, history and the rock beneath so clear as in the case of the Chalk.
Richard Fortey - The Hidden Landscape. Jonathan Cape, 1993

While not all chalk dates from the late Cretaceous, capital C - Chalk - was laid down in great phases at this time. Structurally Chalk forms part of England's skeleton - great limbs reaching out from Wiltshire and Dorset to Sussex and across the North and South Downs; they also embrace the clay on which London lies while the clay itself sandwiches the chalk (the fountains of Trafalgar Square once erupted under artesian pressure from the head of water pressure from the downs). The bastions of the White Cliffs of Dover, the Needles (top right), Old Harry (top left) and the great northern cliffs at Flamborough Head are emblems of England. Continual erosion keeps them glistening, formidable and beautiful. 

We are linked to France by a tunnel through dependable chalk, Monet painted the arch at Etretat, Denmark too has some chalk. But where else in the world do we find such outcrops? It is rare ­ we take it too much for granted.The great arc across the south and east of England coloured green on geological maps with a northern continuation through Lincolnshire and East Yorkshire also marks a time of dying on a vast scale. At the end of the Cretaceous the great dynasties of dinosaurs, ammonites and many others, were gone. In some cultures white is a sign of mourning.

Chalk is fossil organisms in their trillions. Its whiteness, its purity, is the pure calcite manufactured by animals and plants, and here unsullied by sediments from other sources ...
Richard Fortey - The Hidden Landscape. Jonathan Cape, 1993

Chalk is porous, permeable like a sponge. In the landscape chalk faces up to the climate, it stands out as rolling downs and heart soaring vales. Water will only run over its surface when the rain has soaked it through; following the weather with a time lag, sporadic springs and winterbournes emerge.Yet chalk does not make a good building material, being so soft, unless it is protected from above and below (hat and boots) giving us those beguiling walls with little roofs of tile or thatch.

Where it is quite hard at Uffington, Great Wishford in Wilts, Totternhoe, Bedfordshire and Melbourn in Cambridgeshire there are buildings of clunch, small houses and even churches are built of white blocks.The absence of more durable materials also meant the roofs were made of thatch ­ generally straw thatch in the downs where wetland for reed thatch was rare.The one pictured on the right is in Woolstone, near Uffington in Oxfordshire. Some creatures of the Cretaceous built their skeletons with silica (silica dioxide) rather than calcite. After death the silica dissolved and reformed as nodules of flint often in layers marking the then sea floor. These pieces of flint are tough and they fracture in a way that was exploited by our ancient ancestors.

See more FLINT on the BUILDING SITE ...