Ojos del Salado, scientific determination of highest point. Ojos del Salado is, at 6,879m (IGMA), the highest mountain in Chile, third highest in the Andes, and the highest active volcano in the world. It’s located on the Argentina-Chile frontier at 27°06'S / 68°32'W. Its main summit has twin rocky towers, 60m apart and separated by a 30m deep notch, technical on both sides. In February 1937 the Poles J. Wojsznis and J. Szczepanski made the first ascent of the mountain, reaching the eastern tower from Argentina. Nineteen years later, a mainly Chilean team achieved Ojo’s third ascent and the first of the western tower, climbing from Chile. They claimed the first ascent of the mountain, declaring that the western tower was 4m higher. Chile’s Club Andinista denied that claim, accepting the Polish climb, but there has been much discussion about whether reaching the top of the eastern peak is really summiting Ojos. All kinds of opinions have been published, all based on visual perceptions based on simple local observations.

To end the controversy by scientific measurement, an expedition was organized to climb both towers simultaneously and make a topographic leveling between them. A team of eight mountaineers from all corners of Argentina gathered at the abandoned building at 4,500m at the Chilean foot of Ojos known as Murray. There, while acclimatizing, we were trained in the complex technique of topographical leveling by engineer Claudio Bravo, scientific director of the project. After a two-day climb by the normal Northern Route, Rolando Linzing and Dario Bracali reached the top of the western tower on November 11 at 11:30, carrying the 15kg of measuring equipment. A furious wind was blowing, making leveling the field level a hard job. Once that was accomplished, Dario took the graduated ruler to the eastern tower, through an easy technical pass beyond the notch. Rolando made two revised measurements and at 14:30 they started down. That night they reached Murray, where the following day the team analyzed the results.

In conclusion, the western tower is 54 +/-5 cm higher than the eastern one. As this difference is lower than one meter (the minimum that justifies considering a summit higher than another one) it can be stated that both towers of Ojos del Salado have the same altitude. So, the real summit is both of them.

Claudio Bravo (CAT) and Dario Bracali (CAB & AAC), Argentina