Scientists unearth mysteries of giant, moving Moroccan star dune

Structure’s Surprising Age and Desert Drift Uncovered by Researchers

These impressive and mysterious structures, called star dunes, rise out of deserts on Earth and can also be found on Mars and Saturn’s moon, Titan. A team of experts from universities, including Aberystwyth in Wales, has studied one such dune in Morocco named Lala Lallia, uncovering details about its age and formation.

The dune, resembling pyramids from the ground and stars from the air, is located in the Erg Chebbi sand sea. The researchers found that the base of the dune is around 13,000 years old, while the upper part formed in the last 1,000 years. The dune stabilized about 9,000 years ago, possibly due to a wetter climate and vegetation stabilizing the sand.

The star dune’s formation is attributed to winds blowing in two opposing directions, leading to the accumulation of sand. A third steady wind is gradually shifting the dune to the west at a rate of about 50cm per year.

The study used luminescence dating techniques to determine when minerals in the sand were last exposed to sunlight, revealing the age of the dune. This information is crucial for understanding the movement of these dunes, especially when planning infrastructure like roads and pipelines.

The researchers use a luminescence dating technique to determine the age of the sand grains in the dunes. The sand grains can store energy from natural radioactivity, and when brought to the laboratory, they can release this stored energy in the form of light. The brightness of the light indicates the last time the sand grain was exposed to daylight.

To collect the sand samples without exposing them to light, the researchers cut pits into the dunes and inserted an old piece of drainpipe to gather the grains. This part of the process is not very high-tech. However, the subsequent work in the laboratory is highly sophisticated and sensitive, requiring conditions similar to a photographic darkroom.

This luminescence technique has also been used to date remnants of what is believed to be the world’s oldest known wooden structure, consisting of logs along the riverbank between Zambia and Tanzania, predating the rise of modern humans.