The graph below shows our improved data on the time series of the Upper Rio Agrio composition near the bridge in Caviahue. Increased Mg levels indicate the availability of new fresh rock for the hydrothermal fluids (seismic events, intrusion of new magma), whereas decreasing Mg/Cl values indicate the normal trend of a gradual dissolution of rocks by acid fluids, increasing W/R ratios (and causing lower Mg/Cl values). Apparently, the system was active in March and April, and we are currently analyzing the July-October water samples.