As glaciers retreated the volcanoes of the Southern Volcanic Zone in the Chilean Lake District underwent transition from high production rates of volcanic ash and pyroclasts from explosive eruptions to a period of lower ash and pyroclast production associated with a change in magma type from felsic to mafic. Subsequently, felsic magmatism and explosive eruption resumed. All of this has been thought to be linked to changes in the stress field of the volcanoes and their plumbing system caused by unloading of ice. As deglaciation proceeded faster in the north there is an apparent lag in the onset of this behavior among volcanoes. The period of less explosive volcanism spanned from about 17-4 ka BP in Villarrica (39°25' S), 10-2 ka BP in Mocho-Choshuenco (39°55' S), 6-2 ka BP in Puyehue-Cordón Caulle (40°35' S) and Calbuco (41°20' S).