Several rocks have been dated through argon-argon dating and have yielded ages ranging from 1,050,000 ± 5,000 to 250,000 ± 5,000 years ago; among these dates are 271,000 ± 26,000 years ago for rocks in the summit area, 250,000 ± 5,000 for the youngest dated lava flow found just south-southeast of the summit and 544,000 years for the Lomo Escapa lava flow, while the aligned lava domes have been dated to be between 549,000 ± 3,000 and 1,041,000 ± 12,000 years old.