Scientists Reveal The Age Of The Earth’s Oldest Dune Located In Morocco

For the first time, the age of one of the world's oldest and largest sand dunes has been determined by scientists.

Star dunes, also known as pyramid dunes, get their name from their unusual formations and can reach heights of hundreds of meters. They are found in Africa, Asia, and North America, as well as on Mars, but specialists have never been able to determine when they formed.

Lala Lallia Dune

Scientists revealed that the Lala Lallia dune in Morocco originated 13,000 years ago, but the upper part of the structure had only been formed in the last 1,000 years or so.

Lala Lallia (an indigenous Amazigh name meaning "highest sacred point") is situated in the Erg Chebbi sand sea in southeast Morocco. It is 100 meters tall and 700 meters wide, with radiating arms.

The dune originated as a result of the wind blowing in two opposite directions, from the south-west and the north-east, causing sand to accumulate. A continuous third wind blowing from the east is gradually pushing the dune to the west at a pace of roughly 50cm each year.

Following its formation, it halted growing for around 8,000 years before rapidly expanding over the last several thousand years.

Normally, deserts may have been detected in Earth's geological past, but star dunes have been absent until recently.

Professor Geoff Duller at the University of Aberystwyth, who published the research at Birkbeck University, explained this could be because they are so enormous that specialists were unaware they were looking at a single dune.

"These findings will probably surprise a lot of people as we can see how quickly this enormous dune formed, and that it is moving across the desert at about 50cm a year," he said.

The scientists employed luminescence dating to determine the age of the star dune. The approach determines when the grains of sand were last exposed to daylight.

Sand samples from Morocco were collected in the dark and analyzed in a lab under low-red light settings similar to those found in an old-fashioned photographic workshop.

Prof. Duller refers to the mineral grains in the sand as "little rechargeable batteries." They store energy from natural radioactivity within the crystals.

Development Of Star Dune

Researchers said the latest data backs up the notion that the development of the star dune was followed by a shift in wind directions over time.

Star dunes are formed when opposing winds shift direction.

Understanding their age helps scientists comprehend those winds and unravel the environment of that era.

The technique used in the study can be extended to other sand dunes to learn more about Earth's climatological past.

In 2023, the world's oldest known wooden construction was discovered using luminescence dating.

"Using ground penetrating radar to look inside this star dune has allowed us to show how these immense dunes form, and to develop a new model so geologists know better what to look for in the rock record to identify these amazing desert features," said study co-author and sedimentologist Charlie Bristow of University College London.