The industry began in the mid 19th century, when shortage of food after the Napoleonic Wars caused an increase in demand for fertilisers. The coprolite itself is fossilised dinosaur faeces which, when ground up, can be mixed with acid or water to make fertiliser. The dinosaurs are found in a unique area called the ‘Cambridge GreenSand’ which dates the remains from about 110 million years ago. One of the first areas in Cambridge to undergo coprolite mining was Coldham’s Common between the 1850s and 1890s and in 1877 Cambridgeshire was producing practically all of the raw phosphate for fertiliser in Britain (54,000 tons) with a commercial value in excess of £150,000 per annum, a vast sum in Victorian times. Wages were far higher in mining than agriculture so there was a ‘coprolite mine rush’ with huge pits dug on the Common. The making of fertiliser and mining of dinosaur poo began to decline when international competition kicked in from America. But the industry was revived during the First World War when imported goods became unreliable and England needed to grow more food. The miners in the Victorian period were mostly men but during the First World War they were mostly women.