Ojos del Salado was even higher than Ojos del Salado. Later measurements using more precise equipment showed that Ojos del Salado is about higher than Pissis. Furthermore, in 2007 a Chilean–Argentine–European expedition organized by Andes Magazine and Azimut 360 performed a survey on both Ojos del Salado and Monte Pissis using more accurate instruments. It found the former to be and the latter Although this fits within recent handheld GPS surveys, which have estimated the mountain to be between and , the vertical error margin of the expedition's equipment, , leaves uncertainty as to the mountain's more precise altitude. Ojos del Salado has
Aconcagua The colorful greenish, blueish and grey deposits that can be seen in the Horcones Valley and south of Puente Del Inca, are carbonates, limestones, turbidites and evaporates that filled this basin. The red colored rocks are intrusions, cinder deposits and conglomerates of volcanic origin. In mountaineering terms, Aconcagua is technically an easy mountain if approached from the north, via the normal route. Aconcagua is arguably the highest "non-technical" mountain in the world, since the northern route does not absolutely require ropes, axes, and pins. Although the effects of altitude are severe (atmospheric pressure is 40% of sea-level at the summit),