The Age of Earth’s Largest Star Dune Calculated for the First Time
In a groundbreaking discovery, scientists have finally been able to determine the age of one of Earth’s largest and most complex types of sand dune, known as star dunes or pyramid dunes. These majestic formations, reaching hundreds of meters in height, have long fascinated researchers due to their distinctive shapes. Found in various locations across Africa, Asia, North America, and even Mars, star dunes have remained a mystery in terms of their formation timeline. However, a recent study has shed light on this enigma by revealing that a dune called Lala Lallia in Morocco formed approximately 13,000 years ago.
Star dunes are created by opposing winds that change direction, and understanding their age provides valuable insights into the winds and climate of that era. Professor Geoff Duller from the University of Aberystwyth, who conducted the research alongside Professor Charles Bristow from Birkbeck University, explains that “These findings will probably surprise a lot of people as we can see how quickly this enormous dune formed, and that it is moving across the desert at about 50cm a year.”
Lala Lallia, named after its indigenous Amazigh meaning “highest sacred point,” is situated in the Erg Chebbi sand sea in southeast Morocco. Standing at 100m tall and 700m wide, with radiating arms, this star dune experienced a period of growth followed by a halt for approximately 8,000 years. However, in the past several thousand years, it rapidly expanded. The absence of star dunes in Earth’s geological history until now may be attributed to their immense size, which made it difficult for experts to identify them as distinct formations.
To determine the age of the star dune, scientists employed a technique called luminescence dating. This method involves calculating when the sand grains were last exposed to daylight. Samples of sand were collected in Morocco and analyzed in a lab under dim red light conditions reminiscent of an old-fashioned photography workshop. Professor Duller likens the mineral grains in the sand to “little rechargeable batteries” that store energy from radioactivity in the natural environment. The longer the sand remains buried, the more radioactivity it absorbs and the more energy it accumulates. When the grains are exposed in the lab, they emit light, allowing scientists to calculate their age.
Aside from Lala Lallia, other notable examples of these colossal dunes include Star Dune in Colorado, North America, which stands as one of the tallest dunes in the United States at 225m from base to top. Climbing these dunes is no easy feat, as Professor Duller explains, “As you climb, you go up two and slide back one. But it’s worth it – they’re absolutely beautiful from the top.”
The discovery of the age of Earth’s largest star dune marks a significant milestone in our understanding of these natural wonders. By unraveling their formation timeline, scientists can gain valuable insights into past climates and wind patterns. As we continue to explore and uncover the mysteries of our planet, star dunes serve as a reminder of the incredible forces of nature that have shaped our world for thousands of years.
Related Topics: Aberystwyth, Africa, Morocco
