If the word “fjord” immediately makes us think of Norway, a team of geologists have just found traces of these great valleys carved by glaciers in an entirely different region of the world: Namibia. These ancient fjords allow us to learn more about the penultimate glaciation the Earth experienced, but also about the role sea fjords play in the carbon cycle and in climate regulation.
The straits are generally characterized by narrow valleys with high slopes that cut the coast and invaded by the sea, and they represent the coastal landscapes of the countries located in the highlands. Thus it has the potential to influence the climate. Therefore, their study is essential to understanding the evolution of Earth’s climate over geological time. However, there are a few examples of fjords dating back to before the Cenozoic Era, which would allow us to study glaciers before the last Neolithic glaciation. After the formation of the Norwegian Straits. The rarity of ancient fjords must be associated with , which makes them particularly susceptible to corrosion., like Norway, bears witness to the last ice age it went through . These great valleys are the result of labor Glaciers at the continental base. They therefore represent valuable sites for understanding glacier dynamics during major ice ages. but that is not all. The fjords are also centers of very important sedimentary deposits. Therefore, they play a major role in
Monuments of the ancient fjords of Namibia
However, a team of researchers led by Pierre Dietrich from the University of . “This is the first example of a fjord fully preserved”, Explains Pierre Dietrich. “The desert landscape of northern Namibia is actually an ancient ice landscape!”Discover a whole network of ancient fjords on the northwest coast of Namibia. These fjords formed during the penultimate glacier episode dating to the end . This period lasted from -360 to -260 million years ago, making it a particularly long glacial period in Earth’s history. At that time, Namibia was part of
The ancient network of fjords in Namibia today is characterized by valleys that cut a series of plateaus. These valleys, which are now occupied by rivers, are from 1 to 5 kilometers in width and 80 to 130 kilometers in length. Their icy past is not in doubt for Its bottom as well as its sides are marked by traces of the passage of ancient glaciers. Streaks and dents, as well as various marks of friction and wear of the ice, characterize the basement rocks. These effects make it possible to create . The researchers also found An glacier dating back about 300 million years, and consisting of many rock debris. Thanks to these witnesses to the glaciation as well as to the post-glacial deposits above them, She was able to reconstruct the dynamics of the ice sheet at that time.
Ice cover about two kilometers thick
The depth of the cracks, with the depth of the fjords reaching 1.7 kilometers, as well as the presence of many irregular rocks, indicates the presence of an ice cover that completely covered the valleys during the first stage of the glaciation. Thus, the thickness of the ice has exceeded 1.7 km. Flowing in these valleys is fed by a large ice cap located in the far east. This phase of the maximum was followed by a decrease in ice thickness. It is not excluded that this ice age was marked by several cycles of lower extremities, ending with Total invasion of ice and sea in fjords. “Straits also have a very strong control over the stability of the caps because they dry the ice from the caps into areas where the ice is melting and disintegrating. As the ice flows more, the fjords widen under the influence of erosion, which increases the impact of erosion. Fjords. Over time, hats have become more sensitive to climate changes ”, Adds Pierre Dietrich.
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