عربي English Türkçe اردو فارسى
Logo
Latest News
Varieties

Scientists Reveal Secrets of Desert Star Dunes

A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
TT
TT

Scientists Reveal Secrets of Desert Star Dunes

A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS

They are among the wonders of our deserts: star dunes, the vaguely pyramid-shaped sand formations up to about 1,000 feet (300 meters) tall with arms stretching out from a central peak to give them a star-like appearance when viewed from above.
Scientists on Monday unveiled the first in-depth study of a star dune, revealing the internal structure of these geological features and showing how long it took for one of them to form - more quickly than expected but still a process unfolding over many centuries.
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 in a small sand sea called Erg Chebbi about 3 miles (5 km) from the town of Merzouga, close to the border with Algeria.
Lala Lallia rises about 330 feet (100 meters) above the surrounding dunes and is approximately 2,300 feet (700 meters) wide, containing about 5-1/2 million metric tons of sand.
According to Reuters, he researchers used ground-penetrating radar to peer inside the dune and employed luminescence dating to determine how long Lala Lallia has taken to form, a method based on the amount of energy trapped inside the grains of sand. The answer: about 900 years, accumulating roughly 6,400 metric tons annually as wind relentlessly blows sand through the desert.
Star dunes make up just under 10% of the dunes in Earth's deserts and are the tallest ones, surpassing other types such as crescent-shaped barchan dunes and straight and lengthy linear dunes. They also have been spotted on Mars and on Saturn's large moon Titan.
"I first encountered star dunes in Namibia 20 years ago, and was instantly amazed at the size of them. I have a vivid memory of the long climb to the top, struggling up very loose sand in the heat of the day," said geographer Geoff Duller of Aberystwyth University in Wales, co-author of the study published in the journal Scientific Reports.
"I find desert dunes very beautiful," Duller added. "The sight of the sinuous curves, and the way that the light and shadow changes with the sun mean that they always look different, whether that is in the cool of the morning, the midday sun or near sunset. The different colors of sand in different deserts are also very striking, with yellow, white, red and even black dunes in different parts of the world."
The ground-penetrating radar revealed the layers within the Lala Lallia dune, showing how it was constructed over time through accumulating sand and how parts of its internal structure resembled other types of dunes.
"Star dunes are formed in areas with complex wind regimes, which means winds blowing from different directions, and net sand accumulation, points within the desert where big piles of sand can be blown around to form giant dunes," said Birkbeck University of London sedimentologist and study co-author Charlie Bristow.
The researchers also determined that Lala Lallia is moving westerly at a speed of about 1.6 feet (0.5 meters) annually.
While many star dunes are known today, only a single ancient one has been found preserved as sandstone in the geological record, dating to about 250 million years ago, in Scotland. By revealing their internal structure, the researchers said their findings provide a guide for geologists to identify more sandstone remnants of ancient star dunes.
Earth's largest star dunes are found in the Badain Jaran desert in western China. Star dunes also are found in places including the Namib Sand Sea in Namibia, large sand seas in Algeria such as the Grand Erg Oriental and Grand Erg Occidental, and Rub' al Khali in Saudi Arabia. In North America, Great Sand Dunes National Park in Colorado contains a series of them.
"They form extraordinary and awe-inspiring landscapes," Bristow said. "From the ground they can be intimidating, mobile mountains of sand."

Most Viewed

 
 
Varieties

A Herd Stop: Train Kills 3 Rare Bison in Poland

30 May 2016. BIALOWIEZA, POLAND. REUTERS/KACPER PEMPEL
30 May 2016. BIALOWIEZA, POLAND. REUTERS/KACPER PEMPEL
TT
TT

A Herd Stop: Train Kills 3 Rare Bison in Poland

30 May 2016. BIALOWIEZA, POLAND. REUTERS/KACPER PEMPEL
30 May 2016. BIALOWIEZA, POLAND. REUTERS/KACPER PEMPEL

Three wild European bison died on Sunday morning after being hit by a train in Poland's vast UNESCO-listed Bialowieza Forest in the east, the local police told AFP.

According to a police spokesman, a herd of Europe's largest mammals, whose male specimens can reach 900 kilograms (nearly 2,000 pounds), crossed onto the train tracks as a locomotive carrying some 50 passengers between Bialystock and Warsaw aboard was steaming ahead.

"No passenger was injured but three animals perished in this accident, which happened at 7:00 am, near the village of Witowo," spokesman Konrad Karwacki told AFP.

The "Zubr" line train, which takes its name from the Polish word for bison, did not derail and was able to resume its journey around an hour and a half after the collision.

Some 1,200 bison, an emblematic animal in the eastern European country, currently inhabit the Polish part of the great Bialowieza Forest, considered the last primeval woodland in Europe.

The forest, which is divided by the Poland-Belarus border, is a treasure of biodiversity and a giant carbon sink.

Yet several bison fall victim to road accidents in the region every year.

"They are sometimes hit by trains, but these are usually isolated incidents," Professor Rafal Kowalczyk, from a local branch of the Polish Academy of Sciences, told AFP.

"I don't recall an accident where three bison were killed at the same time, run over by a train," the specialist in the giant mammals added.

Devastated by hunting, deforestation and the expansion of agriculture, the European bison nearly became extinct at the beginning of the 20th century.

After disappearing from Bialowieza, its last habitat in Europe, before the outbreak of World War II, the species was saved at the 11th hour thanks to the release of bison reared in zoos back into the wild.

Varieties

Can Nations Save the Shorebird that Flies 30,000 km a Year?

The Hudsonian godwit (Limosa haemastica) is one of the world's most remarkable travelers, but its population has plunged 95 percent in four decades due to a complex mix of environmental changes across multiple countries. Luke Seitz / Cornell Lab of Ornithology/AFP
The Hudsonian godwit (Limosa haemastica) is one of the world's most remarkable travelers, but its population has plunged 95 percent in four decades due to a complex mix of environmental changes across multiple countries. Luke Seitz / Cornell Lab of Ornithology/AFP
TT
TT

Can Nations Save the Shorebird that Flies 30,000 km a Year?

The Hudsonian godwit (Limosa haemastica) is one of the world's most remarkable travelers, but its population has plunged 95 percent in four decades due to a complex mix of environmental changes across multiple countries. Luke Seitz / Cornell Lab of Ornithology/AFP
The Hudsonian godwit (Limosa haemastica) is one of the world's most remarkable travelers, but its population has plunged 95 percent in four decades due to a complex mix of environmental changes across multiple countries. Luke Seitz / Cornell Lab of Ornithology/AFP

Chasing an endless summer, one shorebird species undertakes a grueling annual journey from the Arctic to the tip of South America and back -- a feat increasingly fraught with peril.

The Hudsonian godwit (Limosa haemastica) is one of the world's most remarkable travelers, but its population has plunged 95 percent in four decades due to a complex mix of environmental changes across multiple countries, said AFP.

It is one of 42 species proposed for international protection at a meeting of parties to the UN Convention on the Conservation of Migratory Species (CMS) that starts in Brazil on Monday.

Iconic creatures like the snowy owl -- of Harry Potter fame -- striped hyena and hammerhead shark are also on the list deemed in danger of extinction and needing conservation by the countries they pass through.

Migratory birds are facing "rapid and dramatic declines," said Nathan Senner, an ecologist and ornithology professor at the University of Massachusetts Amherst who has studied the Hudsonian godwit for 20 years.

Scientists are still unraveling the mysteries of the shorebird -- which can fly up to 11,000 kilometers (6,800 miles) in one stretch without stopping to eat, drink, or sleep.

And it is only part of the 30,000 kilometers (18,600 miles) that the godwit travels every year from their breeding grounds in the Arctic to Patagonia where they spend the southern summer.

- Disrupted migrations -

In order to do this "epic flight," they need "really predictable, abundant food resources" at every step of the journey, Senner told AFP.

That predictability is crumbling.

In the Arctic, shifting spring timing attributed to climate change has created a mismatch between when chicks hatch and the peak availability of insects they feed on.

One of the puzzles Senner is currently working on is why Hudsonian godwits have begun migrating later by six days than they did a decade ago.

Something "has either disrupted the cues that they use to time their migrations or their ability to successfully and rapidly prepare for the migration," he said.

In southern Chile, a boom in salmon and oyster farming has led to a build-up of infrastructure and the presence of people in the intertidal zones where they feed.

And in the United States, changes in farming practices are making the shallow water wetlands that the godwits rely on rarer and less predictable -- meaning they spend more time looking for a place to stop and feed.

"I think that is emblematic of lots of species, that most species can respond to one kind of change, but not a whole bunch of them all at the same time," said Senner.

- Essential to ecosystems -

"Climate change is taking a heavy toll on species that rely on a 'geological clock' for their survival; many are disappearing," Rodrigo Agostinho, president of Brazil's environmental agency (Ibama), told AFP.

These are some of the issues CMS parties will tackle at their meeting in Brazil's biodiversity-rich Pantanal, one of the world's most important global meetings for wildlife conservation.

These countries are legally obliged to protect species listed as at risk of extinction, conserve and restore their habitats, prevent obstacles to migration and cooperate with other range states.

Nevertheless, among the species listed under CMS, a report released earlier this month showed that 49 percent now have populations that are declining, up from 44 percent two years ago.

Amy Fraenkel, CMS executive secretary, told AFP that most of the species doing worse were birds, such as the Hudsonian godwit.

She said the situation was also "particularly alarming" for fish species, with 97 percent of those listed under the treaty threatened with extinction.

Migratory species "are essential to healthy ecosystems and a healthy planet," playing a key role in pollination, pest control and transporting nutrients, she said.

In a piece of good news, the meeting will propose removing Central Asia's Bactrian deer from its list of animals needing high protection, due to an increase in its population.

Varieties

Dog Finds Canadian Message in a Bottle on Aberdeenshire Beach

A message in a bottle (Shutterstock) 
A message in a bottle (Shutterstock) 
TT
TT

Dog Finds Canadian Message in a Bottle on Aberdeenshire Beach

A message in a bottle (Shutterstock) 
A message in a bottle (Shutterstock) 

A message in a bottle dropped from a boat off Canada has been found washed up in the north-east of Scotland, according to BBC.

The short letter, written in French and dated in 2024, was found inside the bottle at St Cyrus in Aberdeenshire.

Having travelled across the Atlantic, it was found by one of Mike Scott's dogs during a beach walk.

The 60-year-old said he was “amazed” by the bottle's journey of about 2,700 miles (4,300km).

The professional photographer from Johnshaven takes his dogs to St Cyrus most days for a walk.

He described the weather as “wild” at the time they discovered the bottle.

“As I was walking, Maggie my dog was sniffing a bottle that was just washing up. It was a really dark glass bottle with a lid and something in it,” he said.

He explained: “I had found a message in a bottle before, but it was just from Dundee, so I was not expecting much. There was a zip bag in it, and a letter in French. I put it in my rucksack and put it on translate when I got home.”

The note - which appeared to be signed 'Annie Chiasson' - said the bottle had been put to sea from a ferry travelling between Prince Edward Island and Iles-de-la-Madeleine in August 2024.

Scott said, “So the small glass bottle has survived two winters at sea, travelling from the east coast of Canada, across the north Atlantic, over the top of Scotland and down into the North Sea for us to find at St Cyrus.”

“The sender was asking to let them know if found,” he said. “We found the woman on Facebook, my wife sent a message, but we have heard nothing back.”

BBC Scotland News has also tried to contact the sender.

Scott said, “It was such a weird thing to find, it's not just our own rubbish that washes up. It's amazing it was not smashed. I do not imagine she thought it would end up in Scotland across the Atlantic.”