Résumé
When the transfer periods in karstic systems are too large, about a few years at least, the artificial tracings are no longer valid. Counting the pollen grains present in very small quantities in the karstic hot springs of the Saint-Paul-de-Fenouillet synclinorium allowed us to show that the pollen grains can be used as a natural tracer in a pluri-decennial time scale and provide information about karstic hot springs.