Scientists Reveal Secrets of Earth’s Magnificent Desert Star Dunes

Context: 

Recently, Scientists unveiled the first in-depth study of a star dune, revealing the internal structure of these geological features and the process of its formation.

• The study focused upon a star dune in eastern Morocco called Lala Lallia, meaning “highest sacred point” in the local Berber language, situated within the Sahara Desert.

About Star Dunes

• Star dunes – or pyramid dunes – are named after their distinctive shapes and reach hundreds of metres in height. 
• They are found in Africa, Asia and North America, as well as on Mars – but experts had never before been able to put a date on when they were formed.
• They make up just under 10% of Earth’s desert dunes.
• Formed in areas with complex wind regimes, where winds blow from different directions, leading to net sand accumulation and the formation of giant dunes.
• Star dunes are the tallest and most complex type of sand dunes, surpassing other types such as crescent-shaped barchan dunes and linear dunes.

Formation and Age Determination

• Formed by opposing winds that change direction, leading to the distinctive shape.
• The luminescence dating technique was used to determine the age of Lala Lallia and similar dunes.
• Age Determination Method: It measures the amount of energy trapped within sand grains, indicating when they were last exposed to daylight.
• Allows scientists to understand the wind patterns and climate of the era when the dunes formed.

Global Distribution:

• Found in various deserts worldwide, including the Sahara Desert in Morocco, the Badain Jaran desert in China, the Namib Sand Sea in Namibia, and the Rub’ al Khali in Saudi Arabia.
• Also found in North America, such as at Great Sand Dunes National Park in Colorado.

Lala Lallia Star Dune

• Formed about 900 years ago, located in eastern Morocco within the Sahara Desert, specifically in the Erg Chebbi sand sea near Merzouga.
• Approximately 330 feet (100 meters) high and 2,300 feet (700 meters) wide.
• Moving westerly at a speed of about 1.6 feet (0.5 meters) annually.

News Source: The Hindu