These are awe-inspiring and enigmatic formations that rise up from deserts on our planet, as well as being present on Mars and Saturn’s largest moon, Titan.
Professors from various universities, such as Aberystwyth in Wales, have identified the precise timeframe of a sand dune’s existence in a secluded region in Morocco. They have also revealed insights into how it was created and its movement patterns throughout the desert.
Geoff Duller, a geography and earth sciences professor at Aberystwyth University, described these formations as “remarkable” and “one of the most fascinating natural phenomena in the world.” While they may appear pyramid-like when seen from the ground, an aerial view reveals a central peak with arms radiating out in multiple directions, resembling stars.
A group of University of London scholars journeyed to the southeastern region of Morocco to analyze a 100-meter tall and 700-meter wide sand dune known as Lala Lallia in the Erg Chebbi desert. This particular dune holds cultural significance as its name translates to “highest sacred point” in the Berber language.
According to Duller, the foundation of the dune was found to be 13,000 years old, but they were taken aback by the fact that the top portion of the structure had only been created in the past 1,000 years. It was unexpectedly young.
The base experienced ongoing development until approximately 9,000 years in the past. After that, the surface reached a state of stability. Evidence suggests that the conditions were slightly more humid than they are currently, as old plant roots indicate that vegetation helped stabilize the dune. This state persisted for approximately 8,000 years before the climate shifted once again and this particular star-shaped dune began to take shape.
The researcher, Duller, theorized that the dune’s shape was a result of the wind pushing from the south-west and the north-east. This has caused the accumulation of sand over time. Additionally, a consistent wind coming from the east is gradually shifting the dune towards the west, moving approximately 50cm annually.
“It is crucial when considering the construction of roads, pipelines, or any type of infrastructure,” remarked Duller. “These structures are constantly in motion.”
Revised: Luminescence dating methods, pioneered at Aberystwyth, were employed to determine the age of minerals in the sand by examining the last time they were exposed to sunlight.
According to Duller, our focus is not on the time of sand formation, which occurred millions of years ago. Rather, we are interested in the timeframe of its deposition. The grains of quartz possess a characteristic similar to that of a small, rechargeable battery.
It has the ability to hold energy acquired from natural radioactivity, which can then be released upon returning to the laboratory. This energy is emitted in the form of light, which can be measured to determine the last time the sand grain was exposed to sunlight.
It is necessary to collect sand grains without exposing them to light. To do this, they cut pits into the dunes and used an old drainpipe to collect the samples.
“It’s not a very advanced component,” stated Duller. The tasks performed in the laboratory require a much higher level of sophisticated technology and precision, and must be conducted in conditions similar to those of a traditional darkroom used for photography.
The luminescence method was utilized to determine the age of remains believed to be from the earliest known wooden structure in the world. This structure consists of logs placed along the riverbank that spans across Zambia and Tanzania, existing before the emergence of modern humans.
The findings about the dunes are reported in the scientific journal, Scientific Reports.
Source: theguardian.com
