Lascar is located atop of a ridge formed by the Cerro Corona and Cerro de Saltar lava domes, south and north of Lascar, respectively. Cerro Corona gets its name from a crown-shaped structure at its top. These domes cover a surface area of about . These lava domes are about 5 million years old, and are composed of dacite and smaller amounts of pyroxene andesite, along with rhyolite and visible minerals including biotite and hornblende. An eruption 16,700 years ago from Corona deposited tephra containing biotite and quartz in Laguna Lejía and generated a rhyodacitic lava flow. Another debris flow from Corona spread towards Salar de Atacama.