Guallatiri may have formed during the Pliocene, with a second stage of volcanic activity recommencing during the Pleistocene; the volcano started forming about 710,000 years ago. Two stages of volcanic activity in the Pleistocene-Holocene have been identified, although a three-stage chronology of volcanic activity has been proposed as well; this proposal envisages two earlier lavic stages and a third stage characterized by the emission of pyroclastics and lava domes. Volcanic activity in the Quimsachata volcanic chain migrated south from the now deeply eroded Acotango and Humarata volcano to the more recent Capurata and Guallatiri volcanoes. There is evidence indicating that lava flows forming Stage I of volcanic activity were erupted during the middle Pleistocene and the lava domes forming Stage II were erupted in the Pleistocene-Holocene. The lava bombs on the northern flank suggest that eruptions which produced small amounts of rocks occurred in recent times.