An early pyroclastic flow, the Saltar Flow, is exposed on the eastern flank. It was emplaced after the collapse of the oldest edifice, covering Aguas Calientes' western slopes. The flow deposit was later modified by glacial activity. The Soncor flow is found primarily on the western side of Lascar, with part of it also southeast of Lascar. On the western slope, it buries the even older Piedras Grandes flow, which crops out only at the margins of the Soncor flow. While the Piedras Grandes flow was formed by a glacier run that transported blocks with sizes of up to , Soncor was formed by a large eruption. The large eruption gave rise to a pyroclastic flow that extended westward and contained breccia and various magmas. It was accompanied by a Plinian fall deposit. Finally, the andesitic pumice Tumbres flow is found on the northwest-west-southwestern slopes of Lascar.