The mountain was glaciated in the past, and large valley glaciers descended to elevations of when they reached their largest extent. Later shorter glaciers reoccupied the same valleys; outwash gravel deposits are found downstream below the moraines, such as below the Chalchala and Pocolli valleys on the southern flank of the volcano where most glacial landforms are found. Glacial landforms include glacial striae and ice drift deposits are found on the volcano, as are several extensive moraine systems. Three separate stages of glaciation have been inferred at Tunupa, one dating proposal dates the first advance to about 160,000 before present, the second lasts until about 15,000 years before present and the last one occurred during the Younger Dryas.