If the Sahara desert is hollowed out, what will be left behind?

At first glance, this question seems a little meaningless. Isn't the desert full of sand? Someone asked how deep the sand is in the desert, and what's below after hollowing out the sand? But this question is actually very interesting, because the problem of desertification tells us that places that are not deserts may become deserts. What's under the Sahara desert?

The Sahara desert is bigger than Australia. What's under it?

Almost all of North Africa is a Sahara desert, starting from Western Sahara and Mauritania in the west, including Mali, Niger, Chad, Libya and Egypt, and ending in Eritrea in the east, with a total area of over 9.4 million square kilometers, much larger than the whole of Australia, and almost as big as China and the United States!

Although everyone thinks that the Sahara desert is a long yellow sand, in fact, the area covered by sand dunes only accounts for 15% of the Sahara area. Is the whole ratio a little unexpected to you? The areas covered by deserts are mainly in the central and northern regions, such as Algeria and Libya. The distribution of deserts is still patchy, just like patches on robes!

In addition, the thickness covered by yellow sand in these areas is not uniform, ranging from a thin layer to sand dunes hundreds of meters thick. It is estimated that the depth of sand in some areas of the Sahara desert can reach 320 meters, of course, this is measured from the highest point of the sand dune! And these dunes will change with the strong wind, so the terrain of the desert is terrible, and there may be some differences every day. If you come back in a few months, the sand dunes may not be recognized, and it will be difficult to find the old road in the desert!

In addition to these yellow sands, what may be revealed below is the land before desertification, the desert full of gravel, fertile farmland, forests and grasslands covered with vegetation before, but after desertification, everything disappears! But there is a possibility that although the desert is very dry, there may be groundwater in many places!

Groundwater in the Sahara desert

1In the mid-1950s, when Libya was exploring for oil in the southern desert, a large amount of groundwater was found under the desert. After a wider geological survey, it is found that the water content here can even be described as a lake! Therefore, since the 1960s, Libya has put forward a massive large-scale artificial river project (GMRP), but the actual implementation started from 1984, and the first stage was completed on August 28th, 199 1, and water supply to Tripoli began!

According to research, this aquifer is sandstone aquifer, which was formed in the last glacial period and has no supplementary source at present. However, according to the water consumption rate in 2007, this aquifer can supply water for Libya 1000, but according to the new model, this aquifer may be exhausted within 1000!

water conduit

What was the Sahara desert like in the past and why did it become like this?

A logging company wanted a lumberjack with work experience. A lumberjack said he used to work in the Sahara forest! The interviewer smiled. Everyone knows that the Sahara is a big desert. The lumberjack replied, "This used to be the Sahara forest!"

Sahara forest

Of course, according to archaeological research, even from 35,000 to 8,000 BC, there were still patches of oases in the Sahara region. For example, in southeastern Algeria, Chad and Libya, there are rock paintings showing that a large number of animals were running at that time, and these are buffaloes, elephants, hippos and rhinos that have disappeared in this area at present!

By 4000 BC, the rock paintings found in the Sahara showed that the local animal population had changed and became grazing cattle and sheep. About 700 BC, camels appeared in rock paintings!

We can also know the process of climate change in the Sahara desert from rock paintings, but why on earth did the change become like this?

The Sahara desert has been around for a short time, only a few million years. The past theory was that deserts began to form during the Ice Age about 2.6 million years ago. Glacier cover began to appear in the middle and high latitudes of Europe and North America, and the earth's sea level dropped by more than 100 meters, thus affecting the diversion of warm and humid airflow in North Africa. Deserts began to appear in these areas under extreme drought, and gradually expanded to form a big desert!

But in 2006, a French research team thought that the Sahara desert might have appeared earlier. Through the study of biological fossils in central Chad, they concluded that the Sahara desert began to form about 7 million years ago, at the center or at the end! However, at that time, it did not get wide support from the scientific community!

The latest research results of lasg 20 14 show that the Sahara desert was formed about 700 million-110 billion years ago, and the contraction of the Tethys Sea led to the formation of the Sahara desert in Africa. After using the Norwegian earth system simulation and atmospheric model simulation, the researchers of China Academy of Sciences believe that the Late Miocene Tortonian period (about 7 million years to 165438).

The contraction of the Tethys Sea in the Tortonian caused the summer monsoon in Africa to weaken significantly, and a large area of arid desert environment was formed in North Africa. The contraction of the Tethys Sea not only leads to the change of the average climate state in North Africa, but also strengthens the response of the African summer monsoon to the orbital change, and then becomes the main factor to control the change of the Sahara desert.