For the first time, scientists have calculated the age of one of the largest and most complex types of sand dunes on planet Earth.
Star or pyramidal dunes rise up to a hundred meters in height.
There are them in Africa, Asia and North America, but also on Mars, but it was not known when they were formed.
Scientists recently managed to establish that the dune in Morocco, called Lala lalia, was formed 13.000 years ago.
- Scientists cloned a monkey to speed up medical research
- Amazing new sea life found on 'ocean mountains'
- Scientists solved the mystery of the spread of the multiple sclerosis gene
Star dunes are formed by winds that change direction.
Knowing when they were formed helps scientists understand the climate at the time, says Professor Geoff Duller of Aberystwyth University, who published the research with Professor Charles Bristow, of Birkbeck University.
Lala lalia is located in the southeast of Morocco, it is 100 meters high and 700 meters wide.
It was established that it was formed more than 8.000 years ago.
Scientists are usually able to determine where deserts have been throughout geologic history, but until now they have not found star dunes that old.
The reason may lie in the fact that they did not realize that they were looking at a special dune, says Professor Duler.
"These findings will probably surprise many, because we can see how quickly this huge dune was formed, which moves by about 50 centimeters every year," he adds.
To determine the age of the star dunes, scientists used a technique called luminescence dating.
Using this method, they calculated when the grains of sand were last exposed to sunlight.
Sand samples from Morocco are analyzed under infrared light in a laboratory that resembles an old-fashioned photography workshop.
Professor Duler compares grains of sand to "small rechargeable batteries".
The energy stored inside the crystal comes from natural radioactivity.
The longer the sand is out of reach of daylight, the more it is exposed to radioactivity and accumulates more energy.
When the grains are exposed in the laboratory, they release light energy, which allows their age to be calculated.
"The stronger the light, the older the grains," says Professor Duler.
The highest star dune in America is located in the state of Colorado and is 225 meters high.
Climbing these dunes is hard work, explains Duler.
"You climb two meters and then slide down one, but it's worth it - the view from the top is beautiful," he says.
Watch the video: Scientists in Novi Sad make proteins from agricultural waste
Follow us on Facebook,Twitter i Viber. If you have a topic proposal for us, contact us at bbcnasrpskom@bbc.co.uk
Bonus video:
