History of the Perito Moreno Glacier

Two things almost every visitor believes about this glacier are wrong: that “Perito” was a first name, and that Moreno discovered the ice. Neither holds up.

Hours, prices and access verified by the Perito Moreno Glacier Tours team — last checked August 10, 2026.

The man and the title

Francisco Pascasio Moreno was an Argentine naturalist, explorer and public figure of the late nineteenth century. Perito means expert, and it was his official designation: expert to the boundary commission that settled the frontier with Chile. It was a job title, not a name, and it stuck to him the way titles sometimes do.

He never stood in front of the ice wall that bears his name. He explored the region, mapped and named Lago Argentino in 1877, and shaped the Argentine case in the border arbitration. The naming came later, from others, in recognition of that work.

He was not the first European to record the glacier either. In 1899 the German geographer Rudolf Hauthal proposed calling it Bismarck. The name did not last.

Before any of that

The valley now filled by Lago Argentino was carved by Quaternary glaciation. The ice retreated and advanced repeatedly, leaving the moraines, arms and basins that shape the lake today. The glacier visitors photograph is the remnant of a far larger system.

The steppe east of the ice was the territory of the Aonikenk, also called the Tehuelche, who ranged across southern Patagonia for millennia before the boundary commissions arrived. Guides on the drive from El Calafate often begin the story there rather than with Moreno.

The park

Parque Nacional Los Glaciares was created in 1937, covering 726,927 hectares of ice field, Andean- Patagonian forest and steppe. UNESCO inscribed it as a World Heritage Site in 1981. The walkway network that now carries visitors safely in front of the ice was built and extended over the following decades; before it existed, people watched from the shoreline, which is why it exists.

The ruptures

The cycle that made this glacier famous has been documented since at least 1917. The ice front advances across Brazo Rico and dams the southern arm. Water backs up behind the ice, sometimes rising tens of metres. Pressure opens a tunnel at the contact point, the tunnel widens, and finally an arch of ice collapses into the channel with a noise that carries for kilometres.

The intervals have never been regular. Long gaps have passed with no rupture at all, followed by events only a few years apart. Argentine television has broadcast several live. The mechanism is explained on the geography page.

The equilibrium, and its end

Through most of the twentieth century Perito Moreno held its terminus roughly steady while glaciers around it shrank. Heavy snowfall on the ice field balanced melting at the front, and a submerged ridge kept the terminus grounded. That combination made it a scientific curiosity and a tourism slogan.

The slogan outlived the fact. Work led by Moritz Koch with Pedro Skvarca and Lucas Ruiz, published in 2025, documented frontal thinning accelerating from 0.34 to 5.5 metres a year after 2019, with retreat of around 700 metres a year in the early 2020s. Eighty years of stability ended within a decade, and the brochures have not caught up.

Why the story matters at the balcony

Standing on the central balcony, none of this is visible. The wall looks permanent. Knowing that the front has pulled back several hundred metres a year since 2021, and that researchers are watching a submerged ridge to see whether the ice floats free of it, changes what you are looking at. It is not a monument. It is a process, and it has recently sped up.