Sand dunes are not limited to science fiction, such as the sand dunes that make up the desert planet Arrakis and hide the sandworm known as Shai Khulud, in the work of American Frank Herbert – last week, it appeared for the first time in theaters Sand Dunes: Part 2. Planet Earth is dotted with huge deposits of sand and sand formations, called star dunes.
Among the highest star dunes on the planet are the Lala Lalia Dunes, located in the Sahara Desert in Morocco. This “pile of sand” is 100 meters high and 700 meters wide, and was formed approximately 13 thousand years ago, according to a study that estimated for the first time the age of sand dunes of this type. It is much less time than previously thought. Another discovery is that it moves by 0.5 meters per year.
What is a sand dune?
Sand dunes arise from the continuous accumulation of particles, such as sand grains with a quartz structure, over thousands of years. These particles are carried by the wind and settle in areas that do not have much vegetation. Therefore, they are more common in deserts and beaches.
Star dunes, a specific type, can be defined as “a free-standing dune, with several ridges diverging from a central ridge,” according to the A glossary of geological and environmental terms applied to the earth sciences. Furthermore, they tend to form in areas where wind direction is highly variable, and tend to be higher than other sand dunes.
In simpler terms, star dunes have a pyramid-like shape when viewed from the surface. There is even a central peak. However, when viewed from above, it vaguely resembles a star, with different “arms” created by the force of winds blowing in disparate directions.
And then, see the sand dunes in Morocco:
The highest sand dunes on Earth
At present, the largest known star dunes are located in the Badin Jaran Desert, located in western China. The height of the sand formation is estimated at 300 metres, three times greater than the height of Morocco.
Below, check out a list of some of the highest sand dunes on the planet:
- Badin Jaran Sand Dunes, China;
- Lala Lalia Sahara dunes in Morocco
- Sand dunes in the Namib Desert, Namibia;
- Sand dunes in the Sahara Desert in Algeria;
- Sand dunes in the Rub' al-Khali desert, Saudi Arabia;
- Great Sand Dunes National Park and Reserve in Colorado (USA).
Outside Earth, the two stars have also been found on Mars and on Saturn's moon Titan.
The stellar sand dunes are 13 thousand years old
In an article published in the magazine Scientific reportsScientists at Aberystwyth University in the United Kingdom have been able to calculate the age of the Lalla Lalia star dune in Morocco. In the local language, the name translates as “the highest sacred point.”
How to know the age of sand dunes?
To calculate the age of the Moroccan star dunes, the team of scientists used the scintillation dating technique. Essentially, the strategy allows us to detect when a particular grain of sand, collected from the bottom of a dune, was last exposed to sunlight, based on the level of radioactivity found within it.
In the laboratory, under certain conditions, these grains release energy in the form of light. The more light is emitted, the longer these pimples can “hide”. This helps scientists determine the age of the stellar dunes. Now, the idea is to determine the age of other sand dunes on the planet.
source: Scientific reports, Glossary of terms that it Reuters
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