They are impressive, mysterious structures that loom out of Earth’s deserts and are also found on Mars and Saturn’s largest moon, Titan.
Experts from universities including Aberystwyth University in Wales have now determined the age of a star dune in a remote part of Morocco, revealing details about its formation and how it traveled across the desert.
Professor Jeff Duler, from the Department of Geography and Earth Sciences at Aberystwyth University, said: “They are extraordinary things and one of the natural wonders of the world. From the ground they look like pyramids, but from the air they look like pyramids. You see a mountain peak and these arms radiate in three or four directions, making them look like stars.”
A team also composed of scholars from the University of London went to southeastern Morocco to study a 100-meter-high and 700-meter-wide sand dune in the Erg Chebbi sand dune, named “Lala Lallia”, which means “the highest holy place” in Berber language. point” .
They found that the base of the dune was 13,000 years old, but to their surprise, the upper portion of the structure had only formed in the past 1,000 years or so. “It turned out to be very young,” Durer said.
Construction continued on the base until approximately 9,000 years ago. “Then the surface stabilized. We think it was a little wetter today. We can see traces of ancient plant roots, showing that the dunes were stabilized by vegetation. It appears to have been that way for about eight thousand years. Then the climate started changing again, This star dune is starting to form.”
Durer said the dunes form because winds blow in opposite directions from the southwest and northeast, causing sand to pile up. The third wind blowing from the east is slowly moving westward at a rate of about 50 centimeters per year.
“That’s important when you think about building roads, pipelines or any type of infrastructure,” Durer said. “These things do move.”
Luminescence dating techniques developed at Aberystwyth were used to determine when minerals in the sand were last exposed to sunlight to determine their age.
“We’re not looking at when the sand was formed – that was millions of years ago – but when it was deposited,” Dürer said. “Quartz grains have properties similar to mini rechargeable batteries.”
“It can store energy obtained from naturally occurring radioactivity. When we bring it back to the laboratory, we can make it release the energy. It comes in the form of light. We can measure it, and the brightness tells us the last time the grain of sand Time to see the sun.”
One problem is that they have to collect the sand grains without exposing them to light. They did this by digging holes in the dunes and hammering in an old drainage pipe to collect samples.
“This part is not very technical,” Dürer said. Laboratory work is more technical and sensitive and must be performed under the same conditions as a photographic darkroom.
The same luminescence technique has been used to date the remains of what is thought to be the world’s oldest wooden structure, an arrangement of logs on a riverbank on the border between Zambia and Tanzania that predates the rise of modern humans.
The dune findings were published in the journal Scientific Reports.
