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Prehistoric times in Quercy

Phosphate geology

170 million years ago the local climate was much like that of the tropical sea around the Bahamas today. Richly carbonated mud was deposited that would eventually become the limestone of the Causses du Quercy, along with phosphates from the decomposition of organic matter. At around 70 million years ago the tide went out and Quercy became covered with rainforest. Rainwater seeped into the limestone forming caves and underground rivers at different depths. Simultaneously, an intense erosion occurred on the surface. The carbonates were dissolved. while clays accumulated and concentrated the phosphate. Between 50 and 20 million years ago underground cavities opened trapping the clay and remains of living organisms. The phosphate deposits in the form of concretions (nodules, crusts) and the fossilized organic remains were concentrated in these seams.

Mining the phosphates

In 1865, Jean Andre Poumarède discovered phosphorite nodules on the surface of a field where vegetation grew particularly well near Caylus. Phosphate is a fertiliser and rock phosphate is scarce and therefore expensive. Within five years, more than 300 fields were marked with an army of prospectors. Industrial exploitation started in 1870 producing over 300,000 tons of phosphate a year in just in twenty years. However by 1887, competition from new deposits discovered in North Africa and Florida had started to send this thriving business into decline.

 

Fossils in the phosphate mines

Mining operations caused many fossils to be destroyed although many escaped and they supply paleontological collections and private museums worldwide. Scientists conducted comprehensive descriptive studies of the fossils but early attempts were not successful in dating them. It was not until the 1960s that scientific techniques came through allowing more than 600 species of animals to be identified over 170 sites. They are primarily recognized by the shape of their teeth. Comparison with modern organisms highlight the relationship between species, the influences of evolution and the natural environments of the time. They reveal that between 50 and 20 million years ago Quercy was by turns a tropical forest, savanna and subtropical forest

Visit the Cloup d’Aural phosphate mine

Abandoned for a century and even turned into rubbish dumps, the phosphate mines nearly sunk into oblivion by the 1980s. An association, "Phosphatières de Quercy" decided to develop them, notably the Cloup Aural mine near Bach. The site opened its doors in early summer 2000 and now receives over 10,000 visitors a year between Easter and the November bank holiday. There is a guided tour to discover the mining operations and the fossil flora and fauna. The route takes the visitor from the hot and arid plateau at the surface to the bottom of an abyss of exuberant vegetation and freshness. A discovery trail completes the visit.