Today, the Sahara Desert is a lifeless place with a harsh climate. But it turns out that this was not always the case. We wondered: "Why did the Sahara Desert become a desert?" And that's what we found.
The generally accepted version says that north Africa began to become a desert about 6,000 years ago due to climate change, drying and weathering in the region. There are even funny versions that these people grazed their cattle here, which ate trees, shrubs and grass so actively that devastation occurred. Of course, these versions are broken by other scientists, but no one can clearly answer where and why there is such a large amount of sand in the Sahara Desert.
The fact is that these are not weathered rocks, which differ in structure and contain many impurities, it is sand, almost pure quartz. Such sand is mainly found at the bottom of the seas and oceans, as well as in the deep layers of the soil. This means that something happened that brought huge deposits of sand to the surface. How huge can you imagine if you consider that the average thickness of the sand layer in the Sahara is 150 meters. But what happened? And when?
If you look at the maps from only 500 years ago, there are even more questions. Take, for example, the map of the German geographer and navigator Martin Boeheim, created by him in the form of a globe in 1493.
We see many rivers, lakes, forests, mountains and cities on the territory of the modern desert. That is, the territory of the Sahara was very densely populated quite recently. And this is surprising, because according to scientists, 6,000 years ago it should have been dry and empty. And the Sahara was a truly blooming garden with rivers and forests millions of years ago. But the cards say something else.
Let's look at some more famous maps of that time.
Cartographer Gerard Mercator from Flanders (today it is the Netherlands) in his atlas of 1569 gives a detailed description of the territory of the Sahara and we see many rivers, lakes, cities.
In the atlas of cartographer Abraham Ortelius of 1570, the Sahara also does not look like a lifeless desert at all. And this, by the way, is almost 80 years later than the Boeheim globe.
We also don't see the names of Sahara on any of the maps. After all, Sahara comes from the Arabic “sahra”, which means desert. But she's not here. Rather, there is probably a desert somewhere out there, but certainly not on the same scale as today.
Therefore, to the question: “Why did the Sahara become a desert?” another one was added – when it happened. It can be stated for sure that since the beginning of the 18th century, the Sahara has already been known as endless sand dunes. That is, in 100-200 years there was a total invasion of the sands.
The first thing that comes to mind is a flood, a series of tsunamis that lifted a sandy layer from the bottom of the sea and threw sand deep into the mainland. And we know a lot of evidence of a global flood about 200 years ago, which covered many cities and buildings around the world. But still, this is not 150 meters of sand, and if this sand were from the seabed, it would be mixed with other marine sediments. Therefore, the "megatsunami" version disappears.
But there is another way to produce sand – this is the oxidation of silanes, that is, silicon compounds with hydrogen. Such compounds cannot be detected on the Earth's surface, because when interacting with oxygen from water and air, they quickly disintegrate into sand and water. But underground, in the bowels of silane, they even exist in the form of gases and in the form of, for example, silane oil. This means that in the process of volcanism and degassing, silanes can be thrown to the surface, which will lead to the formation of a large amount of sand.
Is it possible that similar processes of silane release occur in Sugar? Sure. Let's recall at least the famous Rishat Structure, or as it is also called the "Eye of the Sahara".
Previously, it was believed that the eye of the Sahara was a crater caused by a meteorite fall. But upon detailed examination, it turned out that there were no traces of impact, it was not a hole at all, but a bulge, a geological lens. An igneous plume was discovered at a depth under the Eye of the Sahara and in this place magma bulged the surface of the Earth, but did not break through like a volcano. Although igneous rocks have also been discovered. And where there is volcanism, there is degassing.
It turns out that the sands of the Sahara hide from us the geology of this region, and the processes taking place inside. But now we can answer why the Sahara Desert became a desert and how it could have happened in the last 300-500 years.
There are silane deposits under North Africa, which, due to increased magmatic activity, come to the surface and turn into sand. The sahara is like a big spring, from which water flows out and spreads everywhere. Only here silanes flow out and slowly spread out turning into sand.
That's why the Sahara Desert moves 10 km south every year – it grows from the inside, from below, constantly increasing the mass of sand, and the winds carry it over the surface, forming majestic dunes and covering new territories.
