The Fields of Ice Pilgrims
High in the Andes, fields of snow become forests of tall white blades, leaning together like a crowd of kneeling, praying figures.
What was reported
In the high, dry Andes of Argentina and Chile, travellers come across fields of thin spikes of snow and ice, sometimes taller than a person, all leaning in the same direction. Seen from a distance, they look like crowds of hooded figures, which is why they were named penitentes, after the robed penitents in religious processions.
Charles Darwin saw them in 1835 and recorded the local belief that they were formed by the wind. They make crossing mountain passes slow and exhausting.
Explanations offered
Penitentes form where the air is very dry and the sunlight intense. Instead of melting, the snow turns straight to vapour, and small hollows deepen faster than the ridges around them, leaving tall blades that point towards the Sun. Similar spikes have been found on Pluto.
- When
- Described by Charles Darwin in 1835
- Where
- Agua Negra Pass, San Juan, Argentina
- Witnesses
- Mountaineers, Charles Darwin and scientists
- Status
- Explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.
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