Sand digging. Sand from quarries like this is used for a variety of purposes in the building industry. The stratified nature of the sandstone deposit can be clearly seen. The quarry wall behind the digger shows a light-coloured layer of chalk on top of the sandstone. The sand that forms this deposit is thought to have been laid down around 240 million years ago when the British Isles enjoyed a desert-type climate. The picture was taken at the Stone Lane Quarry in Bedfordshire, England.