Many people may think that the Sahara Desert is the largest desert in the world, with an area of more than 9 million square kilometers, which is only a little smaller than China's land area, but it is actually just the hottest desert in the world.
If we are in terms of size, the Sahara Desert can only rank third, and the two largest deserts are the Antarctic and the Arctic, which is somewhat counterintuitive. Although the polar regions are covered with ice and snow, they are dry enough to be called deserts.
How deep is the sand in the Sahara Desert?
Although the Sahara Desert is famous for its sand dunes, most of its surface is made of rock, while the real dunes cover only about 20% of the entire desert surface, mainly located in the north and central areas.
The picture shows: Sahara Desert Map Location
In the dunes in Algeria and Libya, the thickness of the dunes will change because the dunes can accumulate to a height of hundreds of meters, but as the dunes move, the thickness of the dunes will also change.
You read that right, the dunes are moving, it is moving like water in the ocean, and changing the desert landscape, but it moves very slowly.
This is because wind and rain provide kinetic energy, causing ripples on the sand surface. According to measurements, the Crescent Spring dunes in China move about 100 meters per year.
It is precisely because of this movement that it makes measuring the depth of the desert extremely difficult, or we don’t know how deep the sand in all deserts is now.
An estimate shows that the average depth of the dunes in the Sahara desert is about 150 meters, while the top of the dunes can reach depths of up to 320 meters of bedrock (the top height of the dunes is measured from the "sand plane" to be 170-180 m).
In addition, there may be cracks or cracks in bedrock to allow the sand to reach deeper, just like a trench, which we have no way of knowing.
What will be underneath the sand more than one hundred meters deep? Lost ruins, lost treasures, or another magical world!
The Past of Sahara
In fact, the earth is a rocky planet, and the desert is like other places. No matter how you dig, you will eventually encounter rocks.
But the Sahara Desert is different because it has an interesting evolutionary history!
Many people may not yet know that the Sahara was once a fertile region with a prosperous human community.
There are studies showing that the ancient climate in North Africa experienced rapid desertification, and climate change caused the region to transform from humid subtropical landscapes to deserts in just a few years.
and may have experienced this desertification more than once, most recently this time may have happened around 4200 BC, and 13,000 years ago, it just turned from a desert into an oasis.
When the climate begins to change, the Sahara region becomes drought and the plants are withered. Since there is nothing to support the soil, the action of the wind can remove all the fine sediments until sand, rock and bedrock are left.
The essential reason for this climate change may be the change in the inclination of the ground axis.
About 9,000 years ago, the inclination of the Earth was 24.14 degrees, and now it is 23.45 degrees; the perihelion (the point closest to the sun in the Earth's orbit) occurred at the end of July, and now it is early January.
Although the changes in the earth's orbit are gradually taking place, the evolution of climate and vegetation in North Africa is sudden, which means "to move the whole body with one blow".
Sinking civilization and lost cities
From this history of the Sahara, we can know that there will be ruins of ancient human civilizations under it, as well as paleontological fossils, because in dry places it is easier to preserve intact animal remains.
Regarding the ruins of the city, you can imagine that moving huge sand dunes can easily swallow cities and roads. In the past, the Sahara desert did that.
The Galamantes lived in the Northern Sahara civilization from 500 BC to 500 AD. They built complex irrigation systems to maintain urban water conservancy.
They may be the first urban society in the Sahara region without rivers. Unfortunately, the water resources they rely on for survival dried up and their civilization collapsed.
They split into multiple small tribes and were eventually absorbed by the rapidly developing Arab world at that time. And their city was swallowed up by the desert and became ruins under the sand.
Last
The city ruins disappeared in the desert are of course not only this city. The most famous is the desert Atlantis - Ubar (this city has many names, this one is most commonly used). Of course, this will not be the last one, either. .
It is possible that the Sahara will even return to the oasis state over time, which may only change slightly if the planets or stars change slightly.
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