The 36 rhyodacitic lava domes and flows which surround the lake were erupted from about 24individual vents. The eruptions began 25,000years ago, after the onset of deglaciation, and continued until the last such eruption approximately 2,000years ago. After deglaciation 23,000-19,000years ago, two pulses of volcanism occurred at Laguna del Maule, the first 22,500-19,000years ago and the second in the middle-late Holocene. A first, large Plinian eruption formed the rhyolite of Laguna del Maule measuring from a vent presumably located below the northern part of the lake.