Norwegian fjords gave researchers the idea of the birth of a desert landscape in Namibia
The southern African desert is actually a fjord landscape created by glaciers, the researchers suggest.
Not only does the desert landscape have the same characteristic U-shape as many Norwegian valleys and fjords, but the researchers also found rocks moutonnées (rock formations) and glacial streaks in the rock.
Both parts must of course have been made by a glacier.
The researchers also discovered typical moraines formed by ice, as well as the characteristic huge boulders that glaciers have dumped all over Norway.
something very special
But there is something very special about this landscape in Namibia.
It was not, like the glacial landscapes in Norway, created a few tens of thousands or a few hundred thousand years ago.
It is 300 million years old.
How on earth have the glacial streaks and the rocks, the valleys and the mountains, survived all these years in Namibia? They would hardly have done that anywhere else in the world.
The researchers have a theory.
Today’s fjord landscape
- The Namib is a large desert that runs along the coast of Namibia in southern Africa. It is at least 80 million years old and is considered the oldest desert in the world. It is also one of the driest places in the world.
- The ancient fjord landscape of Kaokoland is located in the northern part of the desert.
Fjords in Norway and Greenland have given researchers an idea of what northwest Namibia looked like a few hundred million years ago, NASA’s Earth Observatory reports in a release. hurry.
“It is the knowledge of modern fjord systems that has allowed us to interpret the Namibian valleys as paleofjords,” explains researcher Pierre Dietrich from the University of Rennes in France in the press release.
For those familiar with the landscapes of the Norwegian fjords, it might not be so difficult to imagine that glaciers once shaped the landscape you see in the photo at the top of the article.
And so that’s the idea behind the study that was published in the journal Geology.
Remarkably well preserved
The valleys and fjords formed when Namibia was part of the Gondwanaland supercontinent around 300 million years ago, during a cold ice age in Earth’s ancient history. At the time, Namibia was probably quite close to the South Pole.
Researchers are amazed at how well-preserved these fjords are after around 300 million years, writes NASA’s Earth Observatory.
Many geologists would probably have thought that erosion, post-glacial rebound and other geological forces would have wiped out Namibia’s mountains and glacial landscapes long ago. Geologists believe that it takes 100 million years for mountains to disappear.
A “fossil glacial landscape”
The researchers call what they found a “fossil glacial landscape.”
In other words, a landscape preserved almost like a fossil.
“The ridges looked so fresh and pristine in Namibia that we first thought we had discovered traces of recent glaciers,” Dietrich says.
One theory by researchers as to why this ancient landscape has been so well preserved is that increasingly thick layers of sediment accumulated in the fjords and preserved the landscape after the water disappeared. Outside of Norway, the North Sea is full of such sediments.
The sediments may have effectively shrouded the ancient landscape and ensured its preservation.
Will Norway become like Namibia?
When these sediments disappeared not so long ago, the 300 million year old fjord landscape reappeared with U-shaped valleys, moraines and boulders long before the age of the dinosaurs.
Researchers are now wondering if today’s fjord landscapes in Norway can ever resemble present-day Namibia. Generally, geologists have thought that landscapes like present-day Norway are disappearing quite quickly, in a geological sense.
“What will happen to the fjords of Greenland and Norway in the distant future?” asks the French researcher.
Translated by Alette Bjordal Gjellesvik.
Read the Norwegian version of this article on forskning.no
Dietrich et al. Network of fjords in Namibia: a snapshot of the dynamics of the end of the Paleozoic glaciation, Geology2021. DOI: 10.1130/G49067.1