Why does this massive salt mountain in Algeria refuse to wash away?

Countries & Cities · Published 30 September 2026 Swipe more like this →

In short: Rising from the Ouled Naïl Range near Djelfa, the Rocher de Sel is a striking, barren monolith of salt and clay. Despite its composition, which should be highly vulnerable to the elements, this 105-meter-tall formation remains intact. Scientists are still debating the mysterious mechanisms preventing its total erosion by rainfall.

Known locally as Khanguet-el-Melah, or the Parade of Salt, the Rocher de Sel is a geological anomaly. Spanning nearly 1,500 meters in diameter, the structure is composed of a dense mixture of salt and clay. This unique makeup gives the formation its signature whitish-gray appearance and ensures that the landscape remains entirely devoid of any plant life.

The formation originated when the Earth's crust folded, forcing a buried layer of salt and clay upward into a massive bulge. Over time, precipitation has carved the surface into a scarred, furrowed terrain. Under normal circumstances, such materials would be expected to dissolve or wash away quickly, yet the Rocher de Sel has persisted against the forces of erosion for an unknown duration.

Researchers have proposed several theories to explain this resilience. One hypothesis suggests that the clay content acts as a protective barrier, repelling light rainfall before it can cause significant damage. Another possibility is that the water becomes so rapidly saturated with salt that it loses its capacity to dissolve further material. A third, more dynamic theory posits that the formation is still actively bulging upward, with the rate of tectonic uplift nearly matching the rate of surface erosion.

Whether through chemical saturation, physical repulsion, or ongoing geological growth, the Rocher de Sel remains a subject of scientific curiosity. Its ability to withstand the elements in the Ouled Naïl Range highlights the complex interplay between tectonic forces and surface weathering, leaving the true cause of its survival as one of the region's most intriguing geological puzzles.

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