Geology of Chile the Taitao Peninsula, the Peru–Chile Trench subduction zone is the boundary between the South American and Nazca Plates. At Taitao, the Chile Triple Junction and the Nazca Plate subduct the South American Plate. In Norte Grande the mountains form a series of plateaus, such as Puna de Atacama and the Altiplano. At a south latitude of 27 degrees, Chile's highest mountain (Ojos del Salado) reaches a height of . Below 42 degrees south, the Andes split into a fjord landscape and the highest mountain is Monte San Lorenzo at . As the mountains ebb, the snow line lowers; in the
Ojos del Salado of transverse valleys. Ojos del Salado like other major neighbouring mountains is a complex of lava domes and lava flows, with the main summit surrounded by peripheral domes such as El Solo and El Fraile and many other lateral centres. Fumaroles are encountered at the summit of Ojos del Salado within a depression. Potassium-argon dating has yielded ages of 1.2 ± 0.3 million years ago and less than 1 million years ago from rocks north of Ojos del Salado. There are glaciers on the mountain, in the crater and in the form of penitentes which reach heights of . Other