New study unravels the mystery of Earth’s star dunes

Credit: Prof. C Bristow.

For years, the absence of star-shaped dunes in Earth’s geological record puzzled scientists. These majestic sand structures, characterized by their radiating arms from a central peak, are a common sight in modern deserts across Africa, Arabia, China, and North America.

However, their presence in the ancient landscapes of our planet remained elusive until now. A groundbreaking study by a team from Aberystwyth University, Birkbeck, and UCL has shed light on this enigma, revealing the age and formation process of a star dune in Morocco for the first time.

The research focused on Lala Lallia, a star dune located in the Erg Chebbi region of the Sahara Desert. This area, known for its dramatic landscapes, has served as the backdrop for television series and blockbuster films.

Through the application of luminescence dating techniques, the team determined that the oldest parts of the dune’s base are approximately 13,000 years old.

Yet, what astonished the scientists was the discovery that the dune achieved its impressive size—100 meters in height and 700 meters in width—rapidly over the last thousand years, moving westward at a pace of about 50 cm annually.

This revelation challenges previous assumptions about the age of large dunes and highlights the dynamic nature of desert landscapes.

The study, published in Scientific Reports, utilized ground-penetrating radar to examine the dune’s internal structure, offering insights into how these colossal sand formations come into being.

The findings not only demystify the scarcity of star dunes in the geological record but also propose a new model for identifying such features in ancient rock formations.

The research suggests that the formation of the star dune coincided with the Younger Dryas event, a sudden cooling period that occurred around 12,000 years ago. Intriguingly, the dune experienced a prolonged period of dormancy, ceasing to grow for about 8,000 years.

This hiatus in growth coincides with evidence of wetter conditions, possibly due to an expanded monsoon that stabilized the dune before the onset of a significant drought.

Furthermore, the discovery of pottery at the site indicates human presence and supports the theory of changing environmental conditions that influenced the dune’s development.

The application of luminescence dating techniques, pioneered at Aberystwyth University, played a crucial role in unlocking the secrets of this natural wonder.

These methods, which determine the last time minerals in the sand were exposed to sunlight, are not only unraveling the mysteries of Earth’s deserts but also have broader implications for understanding geological processes related to water resources and carbon storage.

This study marks a significant advancement in our understanding of desert landscapes and their evolution over time. It underscores the importance of technological innovation in geological research and opens new avenues for exploring the hidden histories of Earth’s natural wonders.

As scientists continue to delve into the secrets of star dunes, they not only enrich our knowledge of the planet’s past but also enhance our appreciation for the dynamic and ever-changing world we inhabit.

The research findings can be found in Scientific Reports.

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