Geology Site Account

Ovington Hall sarsen stone

An exceptional sarsen stone, 2 x 1.5 x 0.4 metres in size, with a mammillated surface can be seen near the churchyard on the track leading to Ovington Hall.

Sarsens are extremely hard boulders of sandstone formed around 55 million years ago when the climate of Britain was hot and a layer of sand beneath the surface of the ground became cemented with quartz. They are thus very resistant to erosion and have survived the rigours of the Ice Age. They probably originated on the chalk downland of south Cambridgeshire and after retreat of the ice they became concentrated in river valleys such as The Stour.

The remarkable 'mammilated' surfaces are called growth structures which were formed as the quartz slowly crystallised between the sand grains.

Ovington Hall Sarsen Stone (c.2005)