The hills at the southern tip of Warwickshire, above Long Compton, are capped by beds of limestone of Middle Jurassic age, roughly 170 million years old. These formed as layers of lime-rich shell sand in a warm shallow sea, reminiscent of the modern Bahamas. Fossils are very common in the limestone rock and tell us about the ancient sea-life and marine ecology.
Hundreds of years ago, before the development of the modern life and Earth sciences, fossils were objects of curiosity. The North Cotswolds, in particular were known as a source of so-called ‘pound-stones’: flattened bun-shaped stones that when well-preserved and complete, weighed roughly one pound. As such they were used by dairy workers to weigh out butter and other products.
We now recognise pound-stones as a variety of fossil sea-urchin, closely related to the sand dollars of modern seas. Their scientific name is Clypeus ploti and they can still sometimes be found in the fields and disused quarries at the southern tip of our county.
Locally collected pound-stones can currently be seen in the geological display of the Warwickshire Museum.