Scientists reveal the secrets of ancient desert sand dunes that move across the desert

For the first time, scientists have been able to calculate the age of one of the largest and most complex species of living organisms Sand dunes From Earth, the so-called star dunes, which owe their name to their shape similar to that of a star when viewed from above. This type of dune, also called pyramidal dune, is found in Africa, Asia, and North America, as well as in… Mars. But experts have never been able to pinpoint the time when it was formed.

A poll released this week in Scientific reportHowever, it was revealed that the Lala Lala sand dunes, in MoroccoIt was formed about 13 thousand years ago. Discovering the age of sand dunes helps understand the winds and climate at the time of their formation, as explained by Professor Geoff Doller from Aberystwyth University in Wales, United Kingdom.

“Stellar dunes form in regions with very complex wind systems, which means that winds blow from different directions to form giant dunes in the desert,” explained sediment expert Charlie Bristow of Birkbeck University in London, UK, and co-author of the study.

• Lala lala (which in Berber means “the highest sacred point”) is located in Erg Chebbi, in the Sahara Desert, southeast of Morocco.
• The sand dunes are one hundred meters high and seven hundred meters long. According to the new study, shortly after its initial formation, it remained stagnant for about eight thousand years, expanding rapidly in the past few thousand years.

In general, researchers can include deserts in the geological history of the planet, but not sand dunes. According to Dollar, the biggest difficulty was determining that it was just one sand dune and not several dunes due to their size.

“This discovery will probably surprise a lot of people, because we can see how quickly this dune forms and how it moves across the desert at a speed of about 50 cm per year,” Dowler explained.

To determine the age of the dunes, scientists used a technique called scintillation dating. The method involves calculating the last time the sand grains were exposed to daylight.

Sand samples were collected and analyzed in a laboratory similar to that used to develop photographs, with little red light. According to Dowler, the grains of sand are like “little rechargeable batteries,” storing radioactivity captured from the environment in their crystals.

The longer the sand remains buried underground, the more it is exposed to radioactivity. When sand grains are analyzed in the laboratory, they release energy in the form of light.

“In our darkroom, we see the light coming from these grains of sand,” Dowler explained. “The brighter the light, the longer a grain of sand has to be buried and exposed to radiation.”

Climbing the dunes is hard work, recalls Doller: “When you go up, you have to take two steps up and one step back. But it's worth it, it's so beautiful from the top.”