Scientists have long been puzzled by the absence of giant star-shaped sand dunes in geological records, despite their prevalence in modern deserts around the world. While only one such dune, dating back more than 250 million years, has been found in north-east Scotland, these majestic formations can be observed in deserts across Africa, Arabia, China, North America, and even on extraterrestrial bodies like Mars and Saturn’s moon Titan.
A recent study conducted by researchers from University College London and Aberystwyth University in the UK may shed some light on this long-standing mystery. By conducting a detailed analysis of the Lala Lallia dune in southeast Morocco, the team aimed to develop a better understanding of star dunes and how they can be identified in sedimentary rock.
Revealing the Secrets of Star Dunes
The Lala Lallia dune, standing at a height of 100 meters with radiating limbs stretching out to a total arm-span of 700 meters, provided valuable insights into the formation and movement of star dunes. Using a mineral dating technique, researchers estimated the dune’s base to be around 13,000 years old, with much of its upper formation occurring in the last thousand years. Surprisingly, the dune is also gradually shifting westward at a rate of approximately 50 centimeters per year, highlighting the dynamic nature of these geological features.
Implications for Geological Records
The new analysis of the Lala Lallia dune offers a new perspective on the formation of star dunes and provides a framework for identifying similar features in the geological record. By using ground penetrating radar to study the interior of the dune, researchers were able to develop a model that can guide geologists in recognizing these distinctive desert formations.
While star dunes are primarily shaped by shifting wind patterns, there is still much to learn about these enigmatic structures. The challenge moving forward is to revisit the geological record with the knowledge gained from this study and identify star dunes that may have gone unnoticed due to a lack of understanding of their size and patterns. With advancements in technology, researchers are now equipped to unlock the secrets of these ancient formations and further expand our knowledge of the Earth’s geological history.
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