New Study Reveals Surprising Secrets of Star Dunes in the Sahara Desert
Across the vast expanse of the Sahara Desert, a remarkable sight can be seen: towering star dunes that stand out against the sandy landscape. These unique formations, characterized by their pyramid shapes and spiraling sand ridges, have long puzzled scientists. However, a recent investigation of a star dune in Morocco’s Erg Chebbi region has shed light on their formation and age, uncovering surprising secrets that have been hiding in plain sight.
The study, conducted by a team of researchers using radar scans and analysis of sand grains buried deep within the star dune, has provided valuable insights into the dune’s internal structure. The scientists discovered that the oldest part of the dune’s base formed approximately 13,000 years ago. However, for about 8,000 years, the dune experienced minimal growth. It was only in the past 1,000 years that the dune rapidly expanded to its present size of 0.4 miles (700 meters) in width and 328 feet (100 meters) in height.
These findings have surprised experts in the field. Andrew Goudie, a professor emeritus of geography at the University of Oxford, expressed his astonishment at the rapid accumulation of star dunes. He stated, “I had not suspected that star dunes could accumulate so quickly.” Goudie’s own research on the global distribution of star dunes, published in March 2021, further emphasizes the significance of these new findings.
In addition to uncovering the age and growth patterns of star dunes, the study also revealed that these formations are constantly on the move. Geoff Duller, chair of the department of geography and Earth sciences at Aberystwyth University, explained that the entire dune is migrating at a rate of about half a meter per year. This movement has important implications for infrastructure in desert regions, as it could potentially impact the construction of roads and pipelines.
To unravel the secrets of the star dune, the research team focused their efforts on Erg Chebbi’s Lala Lallia dune, which translates to “highest sacred point” in the local Berber language. Led by Charles Bristow, a professor emeritus of sedimentology at Birkbeck College, University of London, the team meticulously mapped the dune’s structure. They used ground-penetrating radar to produce high-resolution images of the sediment layers beneath the dune’s surface. Sand samples were also collected at various depths to determine the deposition timeline. By analyzing the environmental radiation trapped within individual sand grain crystals, the researchers were able to calculate the age of the dune using a technique called optically stimulated luminescence dating.
The study’s findings not only shed light on the age and growth of star dunes but also addressed a longstanding mystery for geologists. Ancient evidence of star dunes has been exceptionally rare, with only one known example in Scotland dating back to approximately 251.9 million years ago. The scarcity of these formations in the geological record has puzzled scientists for years. However, the researchers suggest that this may be due to a matter of perspective. Star dunes are so massive that eroded parts of their preserved structures may have been mistakenly identified as remnants of other types of dunes. By piecing together these fragments, scientists can confidently identify a star dune.
The study’s findings have opened up new avenues for research and have highlighted the importance of studying these unique formations. Goudie believes that the lack of awareness about star dunes among geologists may have contributed to their absence in the stratigraphic record. However, with the help of tools like Google Earth, scientists now have a better understanding of the widespread presence of star dunes.
The secrets of star dunes in the Sahara Desert are slowly being unveiled, thanks to the efforts of dedicated researchers. As we continue to explore and understand these remarkable formations, we gain valuable insights into the dynamic nature of our planet’s landscapes and the mysteries they hold.
Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American, and How It Works magazine.
