Scientists Unlock the Age of Earth's Largest Star Dunes

In a groundbreaking discovery, scientists have determined the age of star dunes, unraveling the mystery behind these colossal and distinctive sand formations.

Star dunes, also known as pyramid dunes, stand among the largest and most intricate types of sand dunes on Earth, reaching heights of hundreds of meters. Their unique shapes have earned them recognition in deserts across Africa, Asia, North America, and even on Mars. However, until now, experts struggled to pinpoint the timeline of their formation.

Lala Lallia Dune: A Historical Unveiling

In a pioneering study, researchers have revealed that the Lala Lallia dune in Morocco, a prominent star dune, formed approximately 13,000 years ago. Situated in the Erg Chebbi sand sea in southeast Morocco, Lala Lallia stands 100 meters tall and spans 700 meters wide, featuring distinct radiating arms. The age determination of this colossal dune provides valuable insights into the forces shaping Earth's landscapes.

Formation Dynamics and Climate Context

Star dunes, characterized by their pyramid-like structure, result from opposing winds that change direction over time. By understanding the age of these dunes, scientists can decipher the historical patterns of these winds, contributing to a deeper comprehension of the climate during that era. The research, led by Prof Geoff Duller from the University of Aberystwyth and Prof Charles Bristow at Birkbeck University, sheds light on the rapid formation of Lala Lallia, its growth hiatus for about 8,000 years, and subsequent expansion in recent millennia.

Technological Breakthrough: Luminescence Dating

The scientists employed luminescence dating, a sophisticated technique, to determine the age of the star dune. This method involves calculating when sand grains were last exposed to daylight. Samples of sand from Morocco were collected in darkness and analyzed in a lab under dim red light conditions reminiscent of traditional photography workshops. Prof Duller likened the mineral grains in the sand to "little rechargeable batteries," storing energy from the natural environment's radioactivity.

As sand grains remain buried underground, they accumulate more radioactivity and energy. When exposed in the lab, these grains release stored energy in the form of light. The intensity of this light enables scientists to calculate the age of the sediment grains. Prof Duller emphasized the significance of these findings, noting that the enormous Lala Lallia dune formed quickly and is presently moving across the desert at a rate of approximately 50cm per year.

Global Implications

While deserts are typically identified in Earth's geological history, star dunes had remained absent from records until this discovery. Prof Duller speculated that their significant size may have led experts to overlook them as distinct dunes. The revelation of their rapid formation challenges conventional perceptions.

Apart from Lala Lallia, other notable star dunes include Star Dune in Colorado, North America, which stands as the joint-highest dune in the U.S., measuring 225 meters from base to top. Prof Duller acknowledged the physical challenges of climbing these dunes, stating, "As you climb, you go up two and slide back one. But it's worth it - they're absolutely beautiful from the top."

The age determination of star dunes marks a significant milestone in geological research, unraveling the mysteries of Earth's landscapes and climatic patterns. Lala Lallia's historical timeline, exposed through luminescence dating, offers scientists a valuable window into the forces that have shaped our planet's vast and ever-changing deserts.