Due to their instantaneous deposition, volcanic ashes form precise time-markers (tephras) that allow accurate time correlations of sites across extensive areas. Tephrostratigraphy is therefore one of the best tools for correlating long sedimentary records of environment and climate changes. Tephrostratigraphy relies on the principle that the composition of tephras doesn’ significantly vary with distance from the source volcano. Although correlations based on glass shard geochemistry has shown relatively reliable results, the lateral variability of the geochemical composition of such volcanic glasses has yet to be assessed. The recent (June 04, 2011) eruption of the Puyehue-Cordon de Caulle Volcanic Complex (PCCVC, Chile, 40°S), which emitted ashes across large areas of Chile and Argentina, constitutes a unique opportunity to test this hypothesis. The goal of this project is therefore to assess the lateral variations of the 2011 PCCVC tephra by analyzing tephra samples collected in Chilean and Argentinean lakes in February 2012. More specifically, we will assess the variations in grainsize, magnetic susceptibility, and glass geochemistry of the tephras to discuss (1) the in-lake variability (Lago Puyehue, 10 sites), and (2) the long distance variability (35 sites). Ultimately, our results will allow us to assess the potential and limits of tephrostratigraphy in correlating paleoclimate records from different environments, which is urgently needed to understand the interactions, leads, and lags of different parts of the climate system.