Scientists solve mystery behind one of Earth's earliest star sand dunes

The age of the greatest sand dunes on Earth has now been determined by geologists thanks to a ground-breaking study.

These dunes, which are also known as “Star dunes” or “pyramid dunes,” are hundreds of meters high and are recognized for their unique formations, according to a report by the BBC.

They are found in large numbers on Mars and Titan, Saturn’s moon, as well as in deserts, including the sand seas of Africa, Arabia, China, and North America.

Prof Geoff Duller of the Department of Geography and Earth Sciences at Aberystwyth said, ‘‘They are extraordinary things, one of the natural wonders of the world. From the ground, they look like pyramids but from the air, you see a peak and radiating off it in three or four directions these arms make them look like stars.’’

For the first time, scientists have now determined the age of a single star dune in Morocco known as Lala Lallia. The age of the star dune was determined by the scientists using a method known as luminescence dating. The technique determines the last time the sand grains were exposed to light.

For the study, the research team from the UK travelled to the southeast of Morocco to examine the 100-meter-high and 700-meter-wide Lala Lallia. They discovered that the very base of the dune was 13,000 years old, but the upper part of the structure had only been formed in the last 1,000 years or so, The Guardian reported. The dune took 900 years to form, growing by 6,400 metric tonnes every year. After its initial formation, it stopped growing for about 8,000 years and then quickly expanded in the past several thousand years.

These findings, according to researchers, support the theory that the star dune’s formation was accompanied by a change in wind direction over the years.

Birkbeck University’s and fellow study co-author Charlie Bristow explained, ‘‘Star dunes are formed in areas with complex wind regimes, which means winds blowing from different directions, and net sand accumulation, points within the desert where big piles of sand can be blown around to form giant dunes. They form extraordinary and awe-inspiring landscapes… From the ground they can be intimidating, mobile mountains of sand.’’

(With agency inputs)