In Jordan’s Wadi Rum desert, some stones produce a hollow, drum-like sound when tapped together. The effect surprises visitors because the rocks appear solid and heavy. The reason lies in the internal structure of the sandstone that makes up much of the desert’s dramatic landscape.
Wadi Rum sandstone formed from ancient layers of sand that were compressed over millions of years. However, the compression was uneven. As a result, many stones contain tiny cavities, gaps, or layers of varying density trapped inside. These internal spaces allow sound vibrations to travel and bounce within the stone rather than being absorbed immediately.
When a stone is struck, vibrations move through the rock. In stones with internal air pockets, the vibrations resonate, much like sound inside a hollow drum or bell. This resonance produces a clear, hollow tone instead of a dull thud. Stones without these cavities sound flat by comparison.
The desert’s extreme dryness enhances the effect. Moisture normally dampens sound by softening rock surfaces and filling tiny pores. In Wadi Rum’s arid climate, the sandstone remains dry and rigid, allowing vibrations to carry more cleanly.
Not all stones in the desert produce sound. Only those with the right balance of internal cavities and dense outer layers resonate clearly. This makes the phenomenon patchy and unpredictable, adding to its mystery.