Pablo Sigismondi, a geographer from Córdoba, Argentina, was kind enough to send us photos of two nice arches in his country. One is called El Arco (The Arch) on Lake Posadas in Santa Cruz Province (NABSQNO 19G 288494 4736998).
The other is near the small village of Pilolil in Neuquén Province (NABSQNO 19H 333895 5610957).
Natural arches are holes eroded in solid rock, so technically, arches made of ice don’t count. But that does not mean that arches made of ice cannot be beautiful and intriguing objects. One interesting thing about them is that they evolve much faster, although one can imagine natural arches elsewhere in the solar system (such as on outer moons or Kuiper belt objects) made of either water ice or ices of other volatiles that might last many thousands of years.
Interestingly, in Argentina there is a natural bridge made of ice that keeps re-forming and collapsing every few years! In Los Glaciares National Park (a UNESCO World Heritage site) the Perito Moreno glacier advances across a narrow neck between two parts of Lake Argentino, forming a dam. The water level rises on one side of the dam, creating pressure, and the water tunnels through the blocked section, creating an arch. Several years after it forms, usually late in the Southern Hemisphere’s summer, the arch breaks apart in a spectacular crash, and the cycle begins again. The phenomenon has nothing to do with global warming.
The most recent collapse occurred at night, when the Park was closed, on March 11, 2018, so the event was not filmed. Likewise a collapse in 2012 occurred at 3:45 a.m. and there are no pictures.
But the collapse of March 11, 2016, occurred at 10:55 a.m. and was recorded by a large number of tourists. The 4-minute video below shows the event (but misses the final collapse, which can be seen in the following 3-minute video).
This photo taken in 2017 shows the ice bridge has re-formed:
And here is a collapse in 2010 (1-minute):
Another beautiful ice arch collapse is seen in this video of an iceberg in Diskobay, Greenland, in 2015 (2-1/2 minute video):