Research duo reveal secret: mystery of the Moroccan giant dune Lala Lallia solved

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If you want to understand the formation of the desert dune colossi, you must first take a short, exciting physics lesson. Basically there are four types of dunes: there are transverse, straight, crescent-shaped and star-shaped dunes. The 100 meter high Lala Lallia in eastern Morocco is a star-shaped dune. These arise in areas with a lot of sand. When the wind often blows from different directions, the amounts of sand are brought together and form huge mounds that, from above, resemble the lights in the night sky.

How the Lala Lallia, which translates as ‘highest sacred point’, came to be has puzzled researchers. A British duo has now solved this.

A young dune

Geographer Geoff Duller from Aberystwyth University in Wales, together with sedimentologist Charlie Bristow from Birkbeck University in London, reconstructed the dune and its formation. With the help of ground radar, the two were able to determine the age of the dune. The researchers were able to examine the layers in the dune and based on their findings determine how old each layer is. The two British also used ‘luminescence dating’. The amount of energy in the individual grains of sand is measured to determine how long it took for the highest sacred point to form.

Their finds were surprising: the lower layers of Lala Lallia were a whopping 13,000 years old, but the upper part was only 900 years old. The dune is therefore a very young example. Regarding its formation, it can be said that the dune grew steadily for the first 4000 years. But because it was probably quite humid at the time, the surface stabilized afterwards. It remained that way until 1,000 years ago: only then did the structure you see today gradually emerge. About 6,400 tons of sand accumulated annually.

The dune is also moving further and further away from the border with Algeria: the sand giant moves about half a meter to the west every year. (Unpleasant)

Source: Blick