Calcareous tufas result from calcite precipitation under open-air conditions in streams, rivers and lakes in regions where mean annual air temperature is above 5°C. In Europe, these are characteristic of Interglacials and found in almost any area with carbonate bedrock, from Northern England to Greece and from Western France to Poland. Their composition (95 % of CaCO₃) makes them suitable for geochemical research, especially oxygen and carbon stable isotopes (δ¹⁸O and δ¹³C). These parameters have been shown to be important palaeoclimatic proxies in Holocene tufas. At decadal-scale sampling resolution, in modern and Holocene data sets, δ¹⁸O of tufa records variations in δ¹⁸O of regional rainfall, and in this way reflects source or amount effects (particularly continentality), and temperature depending on locality. δ¹³C of tufa indicates moisture availability (linked to biomass type/abundance) and rainfall intensity.
More recently we have been investigating the suitability of δ¹⁸O and δ¹³C as palaeoclimatic proxies in Pleistocene tufas. Using our new results from Pleistocene (mainly MIS 5) sites from Northern England (Alport), France (Caours, La Celle and Condat) and Greece (Zemeno), we can analyse regional-scale variability in climate. Latitudinal variations in stable isotopes should reflect temperature or humidity gradients, or precise respective influences of Mediterannean and Atlantic air mass as rainfall sources.